I'm leaning towards this way of thinking too. If we don't sign Vardy, Wenger will do one of two things IMO, he'll either panic and bring in some squad rotation/stop gap type player and sell us the line that we have Welbeck coming back and that Giroud and Walcott are world class strikers. Failing that I think he'll just promote from within and go with what he has.
Wenger has form for this and has NOT addressed this position for 4 seasons now, he won't spend the money or aggressively pursue options so we're going to be stuck with what we have.
I'd rather we leave this to someone else to rectify because I absolutely do not think Wenger can and will do what is necessary.