Right now, we have just enough evidence to jump to wild conclusions.
If you're the negative sort, you could look at MM over the last six or so months and start to wonder if he's losing interest in DT. He seemed miffed at the compression/production of his drums on DT12 in the one interview, then he's decides to play a few shows for another band, and now we find out he's not in the studio two weeks into recording. Given the level of consistent enthusiasm in his tooooooone when he joined, it isever so slightly noticeable. Maybe the honeymoon is over and Mangini, who is, after all, over 50, is finding this isn't as fulfilling as he wanted. If therewere issues, we likely wouldn't know until a split happened, this being well-oiled PR-machine-era DT. John Petrucci isn't going to take to Twitter and decry Mike's absence from the studio.
Or...if you're the positive type, John Petrucci explicitly noted that they were "planting seeds" for the new album in the last tour, perhaps even early in the tour if I recall. Granted, he/DT have always said they jam and record ideas at soundchecks etc. and occasionally they make it on the album, but it seems like on past cycles, it was always downplayed, like "Yeah, we jam and it's cool, and every now and then, something makes it on." Knowing how carefully Petrucci chooses words, maybe this a real indicator of either a concept album or a change in approach. This is further underscored by the fact that we have yet to see a real studio update two weeks in and that Mike isn't needed in the studio yet.
Either conclusion (or anything in between) has multiple data points that could back it (if you squint), but the meanings of all of them are so fluid that it's all beyond mere speculation (nothing wrong with that, given that we're a fanbase and this is what we have to go on right now). Personally, I suppose I'm more on the optimistic side, but frankly nothing would shock me. Given the nature of DT, anything could be going on behind closed doors. Heck, when Portnoy--one of metal's most communicative, open musicians--left, that came out of the blue. Imagine how little warning we'd get of a member quitting, or other turmoil, in the DT camp nowadays.
Wow, more of this post is about the possibility of MM leaving than I thought. Again, don't think it's likely. Just making a broader comment on the nature of DT information nowadays and where that puts our minds at this point in the cycle. Here's hoping that the latest round of news is evidence of a revitalized band trying new things--or, that they're trying old things with some weird snow delays, and that a great album will come out of it anyway. Disappointed as I've been with their last two releases, I'm going in with reasonably high expectations.
As a complete aside, those of you who were talking about James doing everything in Canada--wasn't he with the band on DT12? I thought it was just ADTOE where he was in Canada. If so, a bit presumptuous to cite as evidence of some sort of drifting apart of the band.