Messi isn't playing like Salah tho anymore, if anything Messi is our false 9 in this comparison and Griezmann is Salah. Messi plays in the same area anyway no matter where you start him on paper and thats mostly somewhere around CM-AM-9 area these days. But it doesn't work out to compare them ofc because Firminho plays the role different than Messi and Liverpool in general plays completely different football.
We need to strengthen the midfield to free him up there so he can play closer to the box if he wants and can just drop back to midfield from time to time and not do the midfielders job in creating too. That was the best part about Messi-Xavi-Iniesta, the midfield already was phenomenal but then Messi dropped back to link up with them and it became unstoppable at times, the past years Messi isn't the cherry on the cake here but HAS to do it because nobody behind him can do it.
That being said i think Griezmann would be perfect to supplement that role for Messi, he is fast, has good movement, can play on the wings as well as central, has a good workrate and good link up play. Seems perfect for a role similar to what Henry/Villa played some years ago. Hope he will join and we will see that at least sometimes next season, with Dembele on RW and Cou at left AM.
100M is a good price considering how much money we waste on average 35-40M players all the time, i mean in the end Griezmann wont cost more than Paco, Vidal and Gomes that's just crazy lol. 100M is still very expensive but at least we get real quality here for once compared to the 200M we burned for the 3 i mentioned + Paulinho, Arda, Digne, Denis, Deulofeu. Griezmann alone will probably have more impact in one season than all these players combined in their whole Barca career. I take one world class player and 2 la masia talents over 3 average la liga signings everyday and financially it's the same thing.
Perfect scenario is we can get most of the money right back by selling at least 4-5 of Vidal, Gomes, Denis, Rafinha, Paco, Deulofeu, Digne but i'd rather not be too optimistic here considering how poor we are at selling players.