So I looked a little further back in the timeline in terms of maintenance of Smash (not all the way to FP1, might do that later)
There's been 2 instances of us getting Maintenance that's not a Main update or Hotfix
-Small Battlefield (On the day of I believe). Also on the day Small Battlefield came out, we also had a delay in Info of Spirit Event or Tournament, though I think it may have only been by like 10 Minutes until Small Battlefield showed uo
-Right before Sephiroth's Presentation (like a few days). The Maintenance was in place probably for the update with Sephiroth's Challenge, which also had Sephiroth and Northern Cave in it, but none of the balancing patches, Spirit Event, or Mii Costumes
Keep in mind the maintenance didn't have the content themselves, it was for preparing for the update when it came
The Time this update is coming out is way Too Early in the morning to be for any type of Shadowdrop, at least the day of. Like with the Maintenance before Sephiroth, we could be in the prepping stages for an update that might contain some Substantial content
I would pay attention to Tomorrow I guess for any Smash Direct or Presentation (or even just a General Direct) announcement. If it involves CP11, then CP11 is also releasing this week, which would be hype. If it doesn't involve CP11, then at least we bound to get something else cool though.