It depends on what the requirement is for getting into the HOF. For bringing UFC more attention and somewhat shaping UFC's future? Probably a yes. For his achievements inside the octagon? I'd say no.
He had a crazy list of opponents, I agree. Couture, Mir, Carwin, Velasquez, and Overeem were no bums. However, his record against these individuals wasn't so impressive. He defeated an aged Couture, had a good win in Mir, a come from behind win in Carwin, and then lost quite embarrassingly to Velasquez and Overeem. 4-3 isn't a record to brag about.
I concede that he is one of the most successful heavyweights in UFC history with 2 title defenses, but hell should the standard really be set at that? The only reason why he is one of the most "successful" heavyweight champion in UFC history is because there isn't really a dominant heavyweight that has fought in the UFC. I believe that the minimum number of times a champion has to defend his title before being considered hall of fame material is 4 to 5. 2 title defenses shouldn't propel you into the hall of fame.
However, with the 2 title defenses and the millions of fans he brought to MMA, I'm sure UFC is considering inducting him into the hall of fame. After he is done with WWE that is.
Anderson Silva ♔
Aldo - Dos Anjos - Mayday - Weidman - Machida - Jones