The same was said 2/3 years ago re Torres.
The answer is that you find the next Suarez who's available for 20M and then use the other 30M wisely. No one suggested selling Torres for 50M cos there was a better player out there in Suarez, but it turned out to be true.
I'm not saying I want us to sell Suarez btw.
Selling your very best player, the best player in the league in fact, is illogical.
Let's say that we do sell for big cash, we will not be in the position to attract established players of similar quality to Suarez as;
a) they are very few and very far between
b) they will already be at a big club in all likelihood
c) we cannot offer champs league.
Truth is I don't know every player in the world and perhaps there is a player as good as Suarez roaming around right now semi undiscovered but he is that good I really doubt it, he is right up in the top echelon in terms of ability.
Either way our chances of finding him and signing him are next to fucking zero.
So that leaves method 2.
We sell Suarez fully in the knowledge that barring miracles we will not replace him with a player as good, but we spend 30M of his transfer fee on other areas of the pitch. Possibly we could strengthen the squad in this way and possibly it might improve us overall but the old maxim a bird in the hand is worth two in the bush applies, we may well just spunk 10M on player A, 15M on player B etc and end up with a team without any player of genuine top class.
We should do absolutely everything to keep him IMO, it is not a debate.