I can see Elves sticking to the bow, instead of the gun. As a matter of fact, I could see Modern Elves all trying to learn Archaic Weapons, and maintaining their Bladesinger and Arcane Archer traditions in a fashion similar to traditional martial arts schools. Keeping their bows would also be a way of maintaining the Elven identity in a world that's leaning more and more towards humanity.
As for the Elves as ecoterrorists, I think that Wood Elves would retreat into primal rainforests and isolate themselves, while High Elves would adapt to the cities and take long walks in the park. Grey Elves would become city planners and bureaucrats, and they'd pretty much be entirely urban. I think Elves would gradually integrate into human society, or vice versa. None of the Elven subraces make sense as ecoterrorists, as that kind of ambition and intolerance strike me more as Human traits.
The Dwarven Kingdoms would stay strong, though I could see the Dwarves developing into constitutional monarchies and gradually evolving into democracies with figurehead monarchies-- with their love of law, I can easily see them embracing a system of laws that even applies to their monarchs.
Dwarves would definitely become mechanics, and I can see them pioneering mass industry-- or refining it after Humans invent it. They might or might not take charge of electronics. Dwarves would definitely take well to firearms, and would establish themselves as master gunsmiths and deadly gunfighters. I see Dwarves leaning stronger towards Soldier than Gunslinger, however.
The Gnomes and Halflings are already well on their way to integrating fully into Human society, so I think this would have already occurred by a modern analogue. They might be a little clannish within Human society, however.
Orcs and goblinoids would have become civilized, though I could see them leaning towards either anarchy or totalitarian states, based on their alignment. There might be pockets of humanoids in the slums of Human cities, or they could be slowly forced into marginal lands , eking out a living. Goblinoids living in Human lands would be in the lower classes in almost all cases, and would probably lean towards crime. They may or may not be suitable for military service, depending on the nation and which species of humanoid.
I think that upgrading a medieval fantasy setting to a modern fantasy setting would make it even more humanocentric, though this is not necessarily the case. If the elves don't die out, and the dwarves expand their influence, it could still hold onto strong racial nations.
Most of the nonintelligent monsters would probably be wiped out, though some of them might be kept alive in captivity. Intelligent monsters could survive if they could adapt to technology-- Dragons could go in either direction, though Chromatic and Gem Dragons would have to learn how to take human shape like the Metallic dragons in order to maintain much influence in the world. With anti-aircraft guns and fighter jets, dragons would have to learn stealth. Subtlety is already a draconic strong point.
If Dragons survive, they would most likely take up politics and business in an attempt to maintain their power and influence. I see them as being very successful at both pursuits. Metallic Dragons would have several advantages in both fields, as they have longer practice in infiltrating Human society, and a better reputation as Good beings. Draconic power might or might not help protect Draconic races such as Lizardfolk and Kobolds.
Illithids and Drow would still be alive, and I think both races would quickly adapt to modern technology. Both races would present heavy opposition to surface races exploring underground, and might sabotage mining efforts for both minerals and oil. The illithids would use their psionic abilities to manipulate surface society, and would probably maintain a kind of Cold War espionage game with surface nations, while the Drow would stockpile weapons and launch occasional raids.
The Drow's inability to work together effectively would keep them from becoming too powerful, unless their society changed (Lloth out of the picture?). Even with magic and technology, their fractiousness would make them ill-prepared to deal with a unified opponent. Drow assassins and terrorists, however, would pull top dollar with organized crime and as intelligence assets.
If magic persisted into the modern era, magical organizations would evolve along with the rest of society, though they would maintain an air of antiquity and arcane secrets. Some would become secret societies, trying to squirrel away their knowledge, while others might become not-so-secret "secret societies" that operate mostly in public. Magocratic nations are unlikely to change, except to become more complicated, and powerful as more magical secrets are unlocked. Most governments would have several magic-users on payroll in some capacity or another.
As long as magic remained prevalent, it would be integrated into society, for the most part.
Religion would remain a powerful force in society, though polytheism would keep a lot of holy wars from breaking out. State religion would be likewise unpopular except for certain rogue nations like the Zhentarim. If the gods become less accessible, religion may wane, or may become dogmatic, which would lead to a state of affairs more closely resembling our history.
If permanent planar gates can be opened, organized trading and colonizing parties would be sent, expanding each realm's influence and leading Prime worlds to contact each other. As the Planes are full of many beings that would not take kindly to conquest, there might be full-scale interplanar wars outside of the Blood War-- or the conflicts may become intertwined. The many different parties concerned would probably hire mercenaries of all kinds, leading to very strange alliances and interactions between races that normally don't have contact.
Spreading technology through the Planes would also have interesting repercussions for religion and general cosmology, and possibly lead to a very rapid development. Infinite monkeys with typewriters, combined with the monkeys being incredibly intelligent and having full access to the counsel of the gods... not to mention, with an infinite amount of resources and space, and magical aid, the various races and nations would spread out significantly.
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