I think it’s also possible that in a world where Chrome/Blink is no longer guaranteed to dominate there’d be increased interest in contributions to WebKit, which is still quite open and flexible, helping bring it up to par for non-Apple platforms.
The "that depend on it" is a past tense analysis. When those "cash-flush multinationals" need to roll out the next version of their product, are they going to continue to bet on a "Blender-style non-profit"?
Or are they just going to ship an iOS app like everyone else since "everyone knows web sucks on Apple now" and "everyone has an iPhone anyway"?
On responding Chrome, I'll add that's partly because Google controlled Search and Chrome which helped Chrome get dominant. Then, web site owners made pages good for Chrome by default. Then, it was harder to compete with Chrome since everyone had to imitate it. If it's independent (or even weakened), that might reverse a bit. Might not.
So, the fact that they're paid to support Google Search means Chrome being divested shouldn't hurt them. The only exception I could see is if they had to pay the new owner of Chrome like that, didn't add anything to the budget, and split it between the two. That's pure speculation, though.
Basically: without Chrome, Firefox dies (Mozilla is mostly a zombie now already) and Apple closes up shop on Safari a-la IE6. The end result of an order like this will be the death of the world wide web as a platform for new applications.