But why not? To me that seems obviously non-rational and ahistorical. People didn't abandon 3.5E when 4E appeared. Quite the contrary in fact - indeed the problem was WotC stopped supporting 3.5E leading people who wanted to keep going with it into the arms of Paizo.
Nor did people abandon 1E when 2E came out, and 4E seemed to have adherents for a number of years past 2014.
If we look at the DDI, it only got shut down in 2020. That was making them way, way, way less money and they kept it going for 6 years after 5E was released. Why would they be more suicidal this time?
Okay so your whole thing here is to assume WotC are (in my words) absolute morons who don't know how to run a business successfully.
Now, you can point to some evidence to support that conclusion I will admit! But mostly they've been pretty successful! I don't think they're dumber than Blizzard, say, and I don't think Blizzard are special super-smart guys.
I don't think you understand how cheap it is to support stuff like this. It's really cheap. Like you would be astonished cheap. But fine, you think they're basically incompetent and so poor they can't do this, okay at least that explains things!
Again, I cannot 100% refute "incompetent" when they dropped at least several and perhaps tens of millions on the disaster that was the 3D VTT/Sigil. I guess I'm assuming they're less incompetent.
The trouble with your incompetence theory (again, cannot 100% refute it lol) is that if it's right, incompetent people never know they're incompetent nor understand how they're about screw themselves, so I don't think them being incompetent actually makes 6E any less likely. On a certain level it might even make it more likely!