Probably worth reflecting that we had an email interop session back in the 90s. This was setup by Dave Crocker and the IETF to put developers for a number of major projects in a room; each with access to code and logs and an a test account on each platform. If you had an interop issue you walked over to the guy working on that platform and worked it out. Fediverse devs are a bit more widespread these days but you could have an online matrix chat or something to substitute for being in the same room. Ideally you would just communicate over the fediverse, but there’s historically an unfortunate and inexplicable aversion to dogfooding in this space.
The fedi will stall and it will be exploited. Whether you like it or not, 5 million people is an untapped market segment. This eventuality will only be a problem for projects that are based on a business plan and that didn’t do a proper risk management assessment. The fedi as a whole should not be affected - as it is an open protocol and doesn’t get to choose who plays.