I understand that VM can have phones that Sprint doesn't, but the One V was a new phone at the time VM added it. If VM gets a phone at the end of its life cycle, they tend to use Sprint phones.
The One S is an "old" phone, as anything a year old is at the end of it's life cycle. The One X, which is basically the same as the One S with LTE added, has already been replaced by the One X+. And, again, the Sprint Evo 4G LTE is essentially a One X/S that was made for Sprint.
It doesn't make sense for HTC to alter a phone to be CDMA when it is at the end of its life cycle -- especially when they make an equivalent phone that is CDMA already. That is a major change to the phone, especially since they would only be making it for Virgin Mobile.
I see two possibilities that I think are more likely than Virgin Mobile adding the One S. One is that Virgin adds the One SV to their lineup, which is a new phone that does have a CDMA version. It actually seems like there is a good chance this is the phone being released, as it seems to fit the general specs and price range of Virgin Mobile phones. The other is that they use the Evo 4G LTE, likely change the stock Android to Jellybean, and rename it (much like the Evo V) to be a "One S".