I read some rumours about gen 4 coming out - it’s just I am desperate to do an evolve session and if there is double xp for the release I want to take advantage! Anyone know?
Summernamechange A gentleman has ‘leaked’ a Gen IV Evolution Event, but it is absolutely not yet confirmed. I posted this earlier in the thread:
He’s basically saying we’ll be getting Gen IV Evolutions of previous Pokémon (eg. Rhyperior, Magmortar, Electrivire etc.), new evolution items, double XP, increased spawns of evolved Pokémon and Gen III evolutions to finally be released in the wild (except Milotic), along with a few other things.
While the source of this ‘leak’ is credible in that they have been correct and successfully leaked before, it is not confirmed, so we can only hope 
I do at least two mass evolve sessions every week, so I’m not saving up ready just in case we get double XP. If we do, great! But it won’t effect my lucky egg sessions.