Steve's body never had a conclusive ending, all that we know is that Wesker's team took his body for experimental purposes and that he may come back similar to Wesker (highly doubtful). In short, considering it's been about 13 years since Steve was taken by Wesker, I highly doubt we will see him again, similar to Barry, Billy, Ark, Rebecca, Sheva and many other RE characters that have simply dropped off the radar.
We finally got Sherry after all this time.
You make a valid point my dear Watson. I suppose it is possible that Steve could reappear (I really want to see some closure for his character) despite the massive time lag considering Sherry came back as a freaking main character (to which I was originally so shocked that my head exploded at the mere idea that Capcom actually brought her back after so many years). Well maybe we'll get lucky, who knows.
When facing a zombie apocalypse, don't join up with a group. Why? Because you'll end up blowing your own head off due to all the pointless drama caused within.