I would stay at Rangers for at least another 2-3 seasons if I were him, unless a really good offer (serious promotion challenger or chance to awake another sleeping giant) comes in.
- Getting Rangers qualified proper for CL will be another fantastic achievement - Celtic has failed to make it to the group stages for 3 seasons in a row.
- Successfully defending the title will be another challenge (keep the players focused and hungry after the gap in points and achievements they managed this season)
- The current Rangers team need rebuilding/tweaking - McGregor (39), Defoe (38), Davis (36) and a host of players in/reaching their 30s (Tavernier, Arfield, Jack, Barisic, Goldson) - chance to show his skills in building/refreshing a team and to leave the club in good stead when he eventually departs (Gerrard and Ross Wilson have begun the process by signing the likes of Ofoborh, Simpson and Wright 21yo-24yo for new season)
- Chance to show his ability to develop players - the likes of Hagi and Aribo have impressed this season