Crap...looks like the promotion/relegation NHL concept isn't going to work. The NHL has some specific hard-coded rules and the entire draft system causes an error as well. I was able to get teams to promote/demote but they wouldn't schedule properly and the fact is when the worst team in the league drafts Jack Hughes at #1 overall and a few weeks later are demoted, that pick can now walk as a free agent.
So my next concept which should be very "do-able" is to bring back the WHA and populate it with the expansion teams and a bunch of entirely new clubs in major markets and regions that are missing top-flight hockey. I'd position the WHA's reputation and finances just a shade under the NHL's - but enough hopefully that WHA teams could legit compete for NHL-level talent like back in the 70's.
The other thing I could do with the WHA is really play around with the rules...the WHA back in the day was something of a rebel league and I'd like to position the new version in the same manner. Maybe use the larger IIHF rinks to attract more European talent and open up space, use a 3-point system for wins, count shootout goals in a player's stats, etc.
I cannot add a WHA draft because drafts are hard-coded, which is a bummer. But I could change the minimum age for the league from 18 to say 17 or even 16 to try and see if teams may be able to sign top level phenoms like Hughes of Kakko or Lafreniere before they are selected in the NHL draft. And lift the limit on the entry level contract salary. So in theory, the WHA's Houston Aeros could sign Lafreniere this season to a big money 3-year deal and he could be playing professionally right now. When the 2020 draft rolls around, he could still be taken with the first pick in the NHL draft but that team would now have to potentially fend off his WHA team for his services and would still be limited to an NHL-standard entry level offer. Thus it would be up to the player whether to stick in the WHA for money or jump to the NHL because it is still the world's preeminent league.
This is all theory of course until I start testing but I actually think this could be quite interesting...