I don't think anyone except City are guaranteed top 4. Chelsea should normally do really well next year too - so it would be quite surprising if they didn't make it.
Of the teams fighting for top 4 I would argue Spurs struggled the most with obvious "holes" last year - which means it should be the team that would be the easier to improve. Not saying Mourinho's coaching was horrible (I don't think it was), but obviously something went a bit left at one point there. Replace Dier with a half decent CD and I think Spurs might have made top 4 so...
I see it being similar next season most likely. If Fonesca (assuming it will be him) can do a slightly better job than Mourinho/Mason - and the defense goes from one of the worst I have ever seen from Spurs - which includes teams with players like Vega, Scales, Atouba etc. in them, to just being average - then Spurs will be right around 4th. Might just make 4th or might end up 6-7th being in the running until the last games.
People pretend this is more predictable than it is. Every year there is another West Ham. A lot of it comes down to finding a bit of groove. Like Spurs did in 16/17, Leicester have done etc. Fonesca looks groovy