It's not the guarantee of success this coming season that Sanchez offers you imo. If we get Dembele, we'll have 5 forward players, 4 of which will be young and relatively inexperienced but expected to provide a significant number of goals and mount a title challenge
Oh I agree but i'm suggesting alternatives because Sanchez isn't nailed on. Any immediate alternative for Sanchez, 20+ goal 20+ assists, will cost the price currently being banded around for Neymar.
Mbappe is the ideal alternative, guarantees you the goals Sanchez can score and is only 18 but you're still talking £130m-£150m in my opinion. Dembele is a cheaper option £80m-£90m who is only getting better. Neymar could be an alternative but you're talking £200m.
Eventually cost will become an issue and if Sanchez isn't attainable then we have to be realistic about which other attackers we could bring in. A big target man isn't really an option given the way we play, so then you're looking at technical, fast, goal scorers and there aren't many around that are available.