It's probably about as likely as Metal Gear Solid 4: Sons of the Patriots getting ported to the Xbox 360. Microsoft has exclusive rights; you can kinda see it as Mass Effect I suppose. Later sequels came to the PS3, but the first game will always remain a Microsoft exclusive.
But, it's not all bad for PS3 owners - and Ubisoft has been gracious enough to give you guys the HD port of the first 3 classic Splinter Cell games:
The disc versions run much better than the digital versions you get from PSN.
If you want to know my personal opinion on it, you can check out my review if you want:
As I said before, a port is not likely... If Blacklist is coming up, and you want to be caught up with the story line you can either watch them all yourself:
http://www.youtube.com/watch?v=sCkiyjS17eg (Part 1, look in 'related videos' to follow the rest - this is not my video btw.)
If you prefer to read the whole storyline, you can read the hefty paragraphs detailing Sam's in Conviction's adventure:
If you still think there will be a Conviction port, I'm not judging you nor do I think you are wrong - but here's just some stuff to help out.