Roll20, FG, and Foundry all seem to have pretty stable, loyal fanbases and I don't see them disappearing any time soon - even if a deep-pockets competitor entered the market. WotC has a notoriously bad track record with digital tools, so I'm not sure their vague (and super secret!!) plans to develop a next-gen VTT is driving anyone's decision making at this point.
Whilst I agree that Astral's reasons for closing didn't relate to this, I am pretty skeptical that no-one is making decisions based on WotC's incredibly poorly-kept secret plans to get into VTTs and so on.
Indeed, I'm pretty sure D&D Beyond has made a number of recent moves largely driven by an attempt to get people as embedded as possible to Beyond and some of their recent cost-cutting decisions look very much like they want to avoid incurring costs for stuff that really largely benefits WotC - like they're no longer implementing UAs, no matter how popular.
I don't doubt Roll20 and FG are also keeping an eye on WotC decides to do, though the big question for them will be whether WotC continues to let them license and sell WotC stuff, and if they do, whether WotC continues to do it in a sufficiently useful way (i.e. ensuring they have it ready for release). There are no answers on those questions yet, but I rather strongly suspect WotC is going to ensure any "beta test" or "early access" material is solely on WotC platforms.
As for a bad track record, sure, but the last time they made genuinely bad decisions re: digital tools was in what, 4E? A very long time ago now, when WotC was a vastly less successful company with different management. I would question the reasoning of anyone going "Well Mearls & co screwed it up in 2008-2012 with their semi-unpopular version of D&D, so Winniger et al will probably screw it up despite having many times as many players, vastly greater revenue, and the world being vastly more online, and it also being vastly easier to develop apps and sites and so on. If WotC want to do it right this time, it'll largely just be a matter of spending money. The only thing that might still get them is a fundamentally bad business model, but that will be a novel issue if so. Doesn't matter how good your tech is if the value proposition is awful enough, as Google can tell you with Stadia. So if WotC manage to do something that looks similarly like a terrible deal, they might not get far.