I really appreciate you taking the time to put all of this down someplace where there are paragraphs. I find this easier to follow than I usually do this length on Discord, and a lot of it makes sense at least as things I hope they're thinking about in development.
I worry that your DEC-based leagues thing basically kills delegation and rentals, though. Those seem like important things to keep. I wonder if it might be reasonable to do something based on staking DEC instead, and add delegating staked DEC, so that people could have the same opportunity to rent their way up leagues as they have to rent cards. (And also it would keep a fair amount of DEC locked up in league eligibility.)
RE: The Incoherent Ravings of a Mad Man