Elon seems to think so. He knows more about this than many of us. He may have reasons to hype the story a bit but I do think he’s sincere.
He also says there is another generation of hardware in the works. Not sure where that fits in. But if they can roll out a 2.5 -> 3.0 hardware upgrade, as they are doing, I don’t see what prevents them from doing that for 3.0 -> 4.0 hardware when the time comes.
Although I don’t know where that fits in, I do know where it does not fit in, which is into a made up narrative which falsely claims that Elon promised the hardware would never change and never be upgraded.
I realize that’s not quite in the spirit of your question but I’m also pointing out that the question may be moot.
Also the qualifier “major” is up for discussion. A replacement of the main computer motherboard certainly seems major on its face, but if it can be done by a mobile service tech in half an hour at a location of your choosing without you even needing to be there, then it’s not so major, in an important sense.