Relax.
Simply having Suarez on the RW with the possibility of rotating with Messi positionally is a huge threat to the opposition defense.
Sanchez does not offer a third of the threat Suarez does in the final third.
And honestly, as long as we win, it doesn't matter who scores the goals. The primary objective is VICTORY. Sometimes, the threat of the striker is more important than the goals themselves if that is what gets you the win.
If Suarez occupies so much space that defenders have to deal with him and thus opens up space for Messi and Neymar to score more, what is wrong with that? Conversely, the same can be applied to Messi/Neymar creating space for Suarez to thrive.
The front three should be functionally mercurial. Having a static front-three is like going backwards tactically.