I've never dealt with a mainframe, so I'll take your word that they are very hard to get off of. What that tells me is to, "just say no" to any mainframe salesman. Stay on commodity hardware and Linux to preserve my autonomy.
It's a long-shot, but maybe WINE will run Adobe Creative Suite (but probably not).
That being said, Richard Stallman saw this coming a long time ago. After years of thinking he was a crackpot, I eventually understood his perspective when he said that it's better to use a Free program with fewer features than a proprietary one with more features. After getting the rug pulled out from under me too many times by proprietary software, I went purely FOSS in 1999. I sometimes have to be creative in my solutions, but I don't consider that to be a bad thing. And my freedom is worth it.
Windows 10/Adobe Creative Suite is a case study in what I have come to accept as Stallman's fundamental truth on the matter, and is the rule of proprietary software rather than the exception.
Retirement means that when someone says "Have a nice day", you actually have a shot at it.