IPv4 is over twenty years old. If MSFT is claiming patent rights in
regard to IPv4 then it seems unlikely that there can be very long
before they expire.
Friend, you haven't done patent law much.
1: If a patent is granted, it's valid until it is
successfully challenged. This lends enormous power to even
inappropriately granted patents and can be used to chilling
effect against even legitimate competition using their own
vaguely similar patented or un-patentable technologies.
US patent rights expire, always have. Old rules 17 years after issue, new
rules 20 years after filing.
Backdated claims are possible but very problematic.
Kindly learn the most basic facts on what you speak before correcting
others.