> The trouble with Firefox chasing Google Chrome compatibility is that, once they get there, Google will probably change something so some Google service is essential to an add-on.
I'd be more concerned that, once they get to Chrome compatibility, they've simply sacrificed one of the key things that differentiates them from Chrome. Firefox's die-hard adherents use extensions heavily, and many of the most popular, particularly those that are on Firefox and not elsewhere, depend on the old XUL layer or other APIs that have no replacement.
I don't think users are going to see it as a great improvement that they have access to Chrome extensions they didn't want in the first place. Instead they're going to focus on the fact that they're losing the functionality that's been keeping them using Firefox.
I don't think you'll need Google to act maliciously or really do anything at all to have this end poorly for Mozilla.