Howe would be a risk but there's only a few manager who wouldn't be considered a risk tbf and not many of them are attainable, and even Mourinho was considered relatively risk free (bring results, negative football) and he hasn't quite lived up to expectations in all fairness. If we finish outside the top 4 this season, that will be 2 out of 3 seasons he has failed to get top four.
Pochettino would be the best bet but even if he would consider leaving Spurs, he would be mightily hard to prise away. He's got a great squad there, new stadium incoming and a young, improving squad. I think he's there for the long haul.