Looks like Benzema is getting ahead of the stake and my money would be on him right now. In a miserable case of Liverpool winning the Champions League and/or some domestic honours, I wouldn't be surprised to see Mane winning it - he's got AFCON and had a great season. Surely deserves some recognition that lad.
Benzema will be the favourite now because Bayern and Lewa are out of the CL, Salah has gone off the boil and Mane has had great moments without necessarily having a dominating season. I'm not sure there are any City players in serious contention this year.
The Champions League is probably still the most important competition in deciding this award and I believe the voting is completed before the World Cup this year so that tournament, which usually has a big say, will not be relevant this time around.
If Liverpool do win the quadruple (and that's a big 'if' because it's going to be very hard and is frankly unlikely) then that would help Mane and Salah, but you wonder if it might end up like Man United's treble year, when it was kind of viewed as a team effort and the vote was split between a few different top players (Becks came second that year IIRC).
A similar thing may happen with City if they win the league and CL double. Unless Salah gets his alien form back, he won't stand apart from Mane and his other teammates as the main Liverpool contender.
In those scenarios, Benz would still probably win it even if Real Madrid don't win the CL, especially since they've revealed this new criteria about 'individual performances' being the key factor.