Paul Farquhar
Legend
Yes, online only seems like the most likely place for any future MtG crossover stuff. It's going to be over a year before there are any more setting books anyway (unless you count the Infinite Staircase mini-setting), and that will be either a Forgotten Realms or Greyhawk boxed set.By valley accounts, the Magic books did really quite well (Ravnica particularly), I would think the issue is more likely to be a realignment of internal politics between teams making big collaborations happening again less likely, now that James Wyatt isn't bridging the gap personally.
Though more Monstrous Compendi seem plausible.