Air Products and BOC will still rent NOS cylinders to industry, it's used in all sorts of processes that aren't going to be banned! There may be some tighter scrutiny of whether the renter / purchaser of NOS has a legitimate industrial usage, and how it might or might not be resold, but NOS isn't disappearing.
As an oxygent for an IC engine it is nothing like as popular for road cars as it was in the early days. The cost and inconvenience of refilling small bottles unless you buy a very expensive transfer pump and decant from full size bottles, the insurance situation, and the amount of damage the temptation of going up "a bit" on jet sizes can do has pushed it back into a very niche market.
My transfer pump is used for TIG and MIG welding gasses these days and my full size NOS bottles went off rental years ago, the refilling and installation demand all but disappeared.
I do have some pistons with totally crushed ring lands in my black museum as testimony to the excesses of young customers though

"It went like hell for a second or two then made this terrible knocking, now it seems to be seized, is it going to be expensive to fix?"
Mentally rubbing hands together, "Yes, I am afraid it is, just get it left over there and then give me the keys".
