Yes.
500 homers gets you in.
Bryce has 184 so far. 500-184 = 316
Bryce has a 13 year contract. 316/13 = 24.3. So basically, if Bryce Harper averages 24 home runs a season over the course of his career, he will get to 500 home runs, which will get him in the HoF. I don't see this being a problem in that bandbox.