For the love of, I'm not mad at you, but it does grind my gears a bit how people beg for stuff ESPECIALLY when it hasn't even come into existence yet. Dynamax could be an awful mechanic everyone despises and then that'd be a waste of all that time planning something nobody wants. Jan already said Gen 8 was on the table to include which is way beyond what you could ask for someone who spends 3-4 times as much time making this game as you think. Just take this life lesson: be grateful for the things you do get even if you are hopeful for more.
No seriously, you don't get full on fan passion projects of this scale other than a sheer few lucky franchises and pretty much all other fandoms would kill to have this many massive projects at this point in production at this quality. You think a Jan or Ame kind of dev is going to just appear out of nowhere and just magically make a free fan game similar to your interest? I'm sorry, but that's wishful thinking. It might, but it might be a few years before something surfaces. I'm sorry to scare you, but you really should think what you ask of people especially if you aren't willing to put forth the effort yourself. If Jan doesn't want to do Dynamax, he shouldn't have to. It's time and work taken away from improving scripts, improving the quality, etc. This stuff doesn't magically come together and work within a week or two.
As for the whole Gen 8 stuff, Jan, I'll give you my simple thoughts: don't ever do something needless that'll start burning you out. There's 800 mons. People can live without 100 of them. But if you and the team are excited and really want to put forth the massive resources for such a project and feat, I say go for it. There's pros and cons for doing and not doing it. You have well over a year to decide on it so it's not something to rush a decision that you'll regret later. Just ignore the people going "Man, I really want Rejuv to implement Gen 8" or "So when's Gen 8 coming?" If you're really a fan of Rejuv, either decision shouldn't be the cause of you dropping the game as that'd be ridiculous refusing to play something just because "Wooloo" isn't in it.
And now with that rant over time for something more enjoyable
OMG GUYZ! ALBA IS ALMOIST DON! CAN I BE EN TAH BETAH AZ I AM A MAD SKILLZ GAMAH! THO THIZ GAME EZ TOO HEARD AND NEEDZ NERD HERD! I STALL BET IT THO! AND I HELPZ HERD! WHAR DO I SING UP?