From my experience, 6 years is about right, maybe a slighty longer than normal.

When IBM purchased Lotus, they pretty left it alone left it alone for 5 years. In 2000 changes started to be forced on Lotus and in a year or two, it was gone.

So, IBM bought RH in 2019, it is now 2025, that seems to have followed their play book almost exactly. I also think other large acquisition proceeded the same way.

Well, luckily there are other distros out there should IBM/RHEL stumble during this "assimilation".

There are not many distros investing so much in the ecosystem - really, there is none. This would be a big, big loss.