HP. The interesting question about him is whether or not he is an agent of Shin Bet; strong evidence exists in both directions.
The worst man in Israeli politics, and that's a high bar.
Oh, believe me, there are worse men.
This piece from Tablet features conversations with people from the movement in which Ben-Gvir originated who see him as a sellout; this sort of thing always goes further than you think.
Will be Prime Minister within a decade.
Nah, he will either be banned from participating (if he is not informing) or be controlled opposition to a "center-left" militarist government who exists to prevent a new Netanyahu coalition from coming into existence (if he is actually an agent of Shin Bet). There is also a dark horse possibility that, as happens oddly frequently to
far-right leaders who become too well-known or too popular for their own good, he will be very conveniently assassinated by some terrorist (as famously happened to Kahane himself, but also his son, and "Gandhi" Ze'evi).