Could WotC mess it up? Sure, but I dont think the bar is sky high either.
I feel like you're underplaying the difficulty of getting this right.
This is something no-one has ever succeeded at, even with 2D, and WotC, are, apparently, aiming to do it with 3D, including 3D maps with elevation (and presumably slopes) and so on. There are bunch of not-great attempts at similar things on Steam.
WotC's advantage is, if what we heard from them last year is true, that they have literally 250 people working on this. That's a crazy number.
WotC's disadvantage is, if what we heard from them last year is true, that they have literally 250 people working on this. That's a crazy number.
The sheer number of people means they can do more, and faster, but also, they're just burning money, huge amounts of money literally millions upon millions. So they're both on a clock, and have to design a product capable of making millions upon millions of dollars, and absolutely will have to compromise the product's design in ways that will make it more suitable for making millions. With a team that large, working for a publicly traded company, you simply cannot wait until the product is perfect, just keeping on burning money - you have to kick it out the door ASAP.
The trouble is, TT RPGs are picky bastards. Very picky and very tetchy, and very pea-under-the-mattress. As we saw very recently with the OGL, they're capable of absolutely rioting if things aren't how they want them, and quite capable of not buying into a novel product. So the compromises they'll need to make to make this financially viable may well also make the product not actually popular with its audience. Thus making it not financially viable.
And one of the likely compromises in making it easy to use, making so simple it doesn't push people away like other VTTs is that it will be nigh-useless for homebrew material. But no, surely they won't do that, surely they have more sense, you say. I don't think so. I think it's very likely it'll launch with a very limited selection of WotC official adventures, not very well or completely implemented, and extremely limited homebrew adventure functionality. But it probably will have a bazillion microtransactions you can, and in fact kind of need to pay for in order to get models for your enemies and PCs. There's no way there will be able to keep that size team once it launches, so the speed of adapting product and adding stuff will also decline sharply after launch.
Because of the way WotC has chosen to do it, and the high-cost approach they've taken, WotC have given themselves a real challenge here. If they had a large indie/AA-size team of like, 15-40 people, they could probably have done this and taken as long as it took, and not had pressure to be ultra-profitable. But that doesn't seem to be the path WotC has taken here.