if a miner minted a block today that had 1 segwit-like TX in it, i seriously doubt that block would be valid.
It would be valid, of course. Perhaps you should consider posting less and studying more? -- not trying to insult, but without the basics you're wasting people's time.
If this stuff is so simple why don't you explain it. If it's too complicated to explain why are you intentional complicating Bitcoin, its not like we don't understand how its supposed to work.
Edit* oops my apologies I eddied my post thinking I was quoting it below.