They are good side, and are on a fantastic run at the moment. The real test will be, can they keep it up? I see their fixtures and think "well, they could slip up here" but they aren't, but the "old" Spurs would. If they maintain this form, then they will be well within a shout of a top 4 place (or higher), but we can't be worrying about them.
On current form, you would say United, City and Spurs are a guarantee for 4th. Arsenal are probably next favourites (based on current form) closely followed by ourselves. But form will change. African Cup of Nations, Injuries, European Football, it will all play a big factor in the teams and their results. Assuming Spurs win their game in hand, that puts them 6 points ahead of us. But, we beat them, and they lose one other (and we win), and suddenly we are level (assuming we match the rest of the results like for like).
That is the fine margins we are talking about here.
Spurs are having their good run, they will hit a bad patch (as most teams do), it is how they get through that will determine where they finish.