Yes and no. An ecosystem can grow, even grow exponentially. But it is sensitive to competitive pressures. VSCode today is so much more widely adopted than anything before it. More than emacs, vim, anything really. So Zed has a good chance because it's simply excellent and many people (myself included) will be motivated to make it happen. But it's not determined that it will succeed in growing a comparable ecosystem.
One thing that works in favour of Zed, which previous IDEs didn't have, is that it's a lot easier to program things today, because of AI. It may even be possible to port many of the more popular extensions from VSCode to Zed with relatively low investment.
Zed's only real differentiator I can see right now is that they're not VSCode, and not run by Microsoft. Their AI isn't really any better than major competitors', and AI integration is table stakes for most new IDEs now anyway. They're missing a LOT of basic features still, their extension system is very lacking, and the extension library us still small.
If the community goodwill can be maintained, and they can expand their extension system capabilities, the community will probably catch them up to the effective VSCode extension library size pretty quickly (at least for a 95% of user's needs cases). But I'm seeing a lot of indications they're headed toward enshitification before they even get fully off the ground. I'm just hoping they avoid the obvious pitfalls of prioritizing only profitable new features and flavors of the month when their only real path to success relies so much on tons of unpaid open source community contributions.
One thing that works in favour of Zed, which previous IDEs didn't have, is that it's a lot easier to program things today, because of AI. It may even be possible to port many of the more popular extensions from VSCode to Zed with relatively low investment.