Our (starting) forwards are not the only thing that needs to be fixed when it comes to the starting eleven. Centre midfield, (arguably) goalkeeper, Holding/Mustafi are solid/good not great. There are a lot more priorities that need to be fixed first before we should worry about 'Plan Bs'.
The fact that he hasn't established himself as a starting player after ten years is testiment to the fact that Walcott isn't that good of player at all. We applaud mediocrity these days.