It's a shame that it's another render image, when the actual minis are often disappointing in comparison. I have the BIG Tiamat and a couple of smaller Tiamats from Wizkids, as well as three Dracoliches. They look fine in person, but when you look at the digital renders, they are disappointing. Especially the seems that don't fit as well as they should...
Naaaah. They are awesome, even up close. I think people who do miniature painting themselves have some ridiculously high standards.
Compare these minis with the ones WotC used to make for D&D or Star Wars. Or heck, compare them with the Wizkids Heroclix minis with their flat cartoony colors without shading.
Yes the human sized minis can have issues, but the big ones are almost all awesome painted.
And the Gem Dragons are the simplest as they don't even really need paint just a color sheen, as they are transparent.
All I can say is... thank f'n G-d! Ever since they announced the newer, smaller black dragon, I was convinced that we'd end up in a similar situation as when WizKids took over the miniatures line and no big green dragon was released for the old Wizards line. I actually just posted to WizKids' social media a few days ago asking if we were ever going to get this.
Luckily, Ve

- whom I have known from my days at the Allspark as a fellow Transformers fan, it is a small world - was put in charge of the fantasy miniature department recently at Wizkids, and he is an attentive guy, he listens to fan feedback on Minisgallery and elsewhere. He knew it was high priority for us fans to get the 5th Gem Dragon at the proper size, so this was one of the first thing he made sure happens! While Wizkids went back to the proper scale of Dragons - no more 1 size bigger due to wing support bases with rings - this one will still be the old size.
I am really looking forward to the Monster Menagerie Revisited set too, knowing he wants to give us the minis we have wanted for years to happen (Gorgon, Bar'Lgura, Hezrou, lot more) still done in the pre-MM2025 style.
(Edit - LOL for some reason his name getsturned into an X-Wing logo? Is that some Enworld feature?)
If little crystal bits aren't floating around the miniature . . . get on it Wizkids!
Sadly, ioun stone technology is too expensive to use for toy manufacture...

The way they do it is with transparent pegs holding them in place, it is OK. See my Topaz Dragon pic's back frill.
Most of those that were in the pre-painted minis 'space' have left it. One of the biggest ones left is Renegade Studios with Heroscape and it's line of prepainted miniatures. They actually show bot the drawn illustration and a photo of the painted miniature on the front cover of the box. Archon Studios is also doing stuff with terrain being printed on (not so much painted), but compared to Wizkids they are a far smaller niche. Wizkids doesn't just do the D&D prepainted minis, but also the Pathfinder, Critical Role, Heroclicks (Marvel & DC), Magic: The Gathering miniatures, etc.
Personally, I prefer the old WotC D&D minis over the Wizkids ones...
Generally, at the time of preorders there is no printed sample yet they could show. Usually 1-2 months before release, the Wizkids store page gets updated with photos of a prepainted copy, or they share them on Twitter or Instagram. For example, photos of the Pathfinder Adult Diabolical Dragon just got uploaded on Instagram yesterday.