You're probably right.
But Walcott is older than Welbeck and it seems that Wenger prefers Welbeck as well, if recent games are anything to go by.
The problem we have, is we have several strikers, Welbeck, Giroud, Perez and possibly Walcott, but we need a world class one, which none of these are.
So one or more of them are surplus to requirements, and with Walcott's, age, wages, injury record and inconsistency taken into account, I would think he could be the player to go.
We could get at least 25-30m for him and that would go towards getting a world class player.