I think there will be the occasional new spell that will be a "mistake" spell from WOTC (TC ish), but most of the new spells will just be ok/good in standard and be based around creatures.

Basically I'm expecting standard to revolve around midrange for now on. Control will get just enough to kinda make a control deck and some times it'll be actually good "traditional control". Aggro will be slower and really more mid rangy burn. Combo might be a thing, but to what extent is unknown. I doubt a "twin" combo will ever be a thing even at 6+cmc, something like ascendancy will come around ever so often (but never be good), and the "aristocrats" style of combo decks will be the closest we get.

I expect a new "Goyf" fairly soon. Weather it's good or not outside standard is up for grabs, but some hyper efficient 2 drop that does nothing but beat seems like it would fit right in.

I expect a swagtust/rhino in every set form now until the end of time, with a hangerback at least every other year.

I expect some good removal at 2-3 cmc that'll be used outside standard which will keep people saying "But this card is playable in modern, quit bitching", but in reality it's just a slight upgrade to a flex slot in most decks.

The man bases will shift around, WOTC is very good at that. People will bitch bitch bitch about the mono blocks though. If black/blue are the dominant colors just RIP that standard block as no one will let THS-RTR be forgotten.

I would be really surprised to not see some "affintiy" lite deck within the next few years. I really think wastes will let WOTC push some more powerful colorless decks and I think aggro would make some people really happy.