Yeah I wish people would stop seeing this in the context of Sanchez. Sanchez is gone, we've already fucked that up and there was no way on earth we were ever going to get anyone on his level to replace him. The same with Fabregas, van Persie, Henry.
If Ozil stays then a finisher up front will be very useful. A front 4 of Lacazette, Ozil, Someone Good & Someone Good probably makes for a better team than Sanchez, Ozil, Chamberlain, Walcott, even if the "Someone Good"s aren't Sanchez level.
I seem to remember us getting more points the year we lost the irreplaceable "we'd be 7th without his goals" van Persie because we ended up buying a better attack. Cazorla and Podolski replacing Ramsey/Rosicky and Gervinho had a better net impact on our side.