That's exactly what the Mill CPU folks are trying. I have hopes for a RISC-V vendor to do this too.

However, being a monopolist makes certain things illegal for you to do, and some of those things are things that are easy to suspect you of, but hard to prove you're not doing.

As such, being a monopolist constrains you, as well as invites long, expensive, frustrating probes into your business that creates costs and risk (even if you're not intentionally violating anti-trust law, doesn't mean some business unit isn't inadvertently doing so).

E.g. IBM was under an anti-trust probe from 1969 until 1982 over their mainframe business. The probe ended with the DOJ concluding the case was without merit, but it is widely considered to have had a big effect on IBMs decisionmaking for more than a decade.

That being said, any market they can compete with Intel and cause them to have less than 100% marketshare in while making money is a market they are in or want to be in if they aren't already.

Intel literally has a half decade of chips that they could release right now that perform better and are ready to be released, but won't be until years down the road due to a desire to remain top dog in the event they have another Pentium 4 happen.

Perhaps that Joint Venture will go as well as Intel Israel went (brought the Core series out, replacing the failed Pentium 4) which then replaced Intel Oregon, but that is an iffy bet. The Israelis are particularly good at critical thinking, whereas that is generally not encouraged in China. I might be wrong though, but 2 to 3 years from now when we see first silicon for their modified Zen, we'll know.