Every team is a threat in some form... Wolves and Cardiff for example gave us very good games last season. Other clubs vying for top 4 or a genuine challenge are about to go all in I reckon.. Rags will sign a decent few players, Bale, and Aulderweild mooted. Chelsea might have Sarri, Spurs might improve under Pochetino and Liverpool are starting to spend.
I see other clubs moves triggered not only through fear of being left behind by us, but the teams realising they are so far behind Spain it's embarrassing.