I wouldn't be surprised if we don't see a "replacement" as such bought in for Mane. Depends on if the staff think Rodriguez can stay fit and hit form and whether Juanmi will progress next season, coupled with the likes of Hesketh and Sims pushing the squad. I'd really like us to spend big on Sigurdsson this summer though, so selling Mane, using Rodriguez as his replacement and signing a back up wouldn't make me unhappy.
For Wanyama, I have no clue. It'll be someone from abroad we know very little about.