Let's not forget that Google's spam filtering racket has made it next to impossible to host your own email in any kind of practical manner, or even use many hosted email services effectively over the years.
This. I hosted my own email for over 15 years, and last year was the year I gave up. There was nothing wrong with my machine's IP, I was doing the right thing email server wise, but Gmail still didn't let me deliver. A racket is a good way of describing it.
Absolutely. I set up my own domain last year, hoping to run a mailserver directly off it. The whole thing was perfectly configured, but the 'some dude' IP address made it unusable. Eventually I moved the domain's hosting to Fastmail, and now the mail actually arrives.
Users may not switch (right away) but how we as a community talk about this problem can switch. This will ultimately help the problem get fixed when perceptions shift, either within Google or by new users evaluating other options given Google’s reputation of poor deliverability/interoperability.
Also I suspect a lot of Google’s early adopters will be switching away due to this change. These are the tech-savvy evangelists who helped build Google Apps to what it is, and can plausibly do it for another service too.