Ruin Explorer
Legend
No way would either of these happen.
- Cleric because mythology-inspired settings need gods and religion
- Monk because of Asian influences on modern fantasy, especially shonen manga
Monks are pure 1970s. Absolute pure 1970s. There is no other decade in the 20th or 21st centuries where that class could have been developed. Not one. Even if we just shifted to the 1980s, Monks would be out, and the "martial arts" class would be Ninjas.
Instead if it was like, any time in the last 20 years, we'd have some kind of martial-artist class, but one that owed vastly more to - yes shonen manga as you say, and to videogames like the Street Fighter series. They would be absolutely nothing like D&D's Monk except that they'd fight unarmed and unarmoured by default. They wouldn't necessarily fast or agile, particularly - many of these characters are big bruisers - they wouldn't all have similar abilities at all - they'd probably have a large array of abilities to customize themselves with, and could probably be STR or DEX-type based (or whatever similar stats the game used).
Clerics would never happen. They're a freak of nature. D&D does not have them because you need gods and religion, and gods and religion don't require heavily-armoured mace-wielders with massive magical powers. They only happened in D&D because there was a Vampire PC (he had his own class and everything), and another player wanted a class to counter him, so they sort of mashed up Bishop Odo and Van Helsing and ton of largely Abrahamic myth for the spells. This worked unexpectedly well so we have Clerics today and whilst D&D has revisited a Vampire class (in 4E for example), it's not been a permanent addition.
You might have a priest-type spellcaster, but they'd be a robe-wearer, and probably have a lot more in common with the Warlock than they do with any form of priest/cleric character in D&D.
Otherwise I think a lot of your guesses are not bad at all!
Barbarian/Fighter/Rogue could very easily be one class picking abilities too - the sort of characters in fiction who fit that have massive crossover with each other.
I think one thing people are missing is a Dark Knight/Vampire Knight-type character - this concept predates D&D by a fair way, and it often pops up in quite non-D&D-ish fantasy. It's actually weird as hell D&D doesn't have one, I think because "bad Paladin" often occupies similar thought-space.