UPN doesn't really exist anymore. They realized that they couldn't build a network around just Star Trek, so they refocused to target black people, and then they decided that Star Trek didn't really fit with their plans anymore. And then when that plan failed, they merged UPN with Warner's WB to make CW, which now apparently mostly targets Twilight fans.
I think if CBS wants to have a new Trek either to support their main network or for CW, the show will be different, depending on where they want to put it.
If CBS makes the show for syndication, that means they're making the show to sell it to other stations, not for themselves, at which point anyone with enough money could maybe buy it and air it, including SyFy. (This seems unlikely, if you ask me. They wouldn't want to make Trek just to sell it and make some money, they'd want to maximize their money somehow, otherwise it's not worth doing.)
If they don't want Trek but still want money, and they arrange some sort of deal where SyFy covers most/all of the costs of making the show, then maybe SyFy will get to air it.
Also, if CBS makes the show for themselves (or CW), they might sell the reruns in the syndication market, which would mean that SyFy might air rerun episodes a year or two after CBS airs them.