We see Clu and Tron fighting over Light Jet baton and Clu steals it. After that, Tron is seen descending into what looks like water. Is there any information what looked to be water in the program world , that Tron fell to the depths and drowned in the substance? Is there anything that explains what happened?
We don't know.
Tron's ultimate fate isn't made clear in any of the film's associated media. We know from Tron: Uprising that brief immersion into the Sea of Simulation isn't fatal and we see in Tron: Betrayal that ISOs are actually born in the sea, prior to its being poisoned by Clu.
That being said, there's every indication that the sea, especially in its poisoned state is deadly to basic programs since it was intended to act as a physical barrier to the portal.
He probably drowned although he did enjoy a moment of redemption just before he died.
tl;dr: Impossible to say at the moment.
Out of universe, since Bruce Boxleitner (Alan Bradley / Tron's original actor) isn't getting any younger, chances are we won't see Tron in a live action movie anymore. But...
(Spoilers are from Uprising, towards the final episodes!)
As Valorum mentioned, what Tron fell into is (most likely) the Sea of Simulation, and having been poisoned, Tron's chances of survival are reduced - let alone the question whether programs can actually "swim". However, (especially if you've seen Uprising, you'll know) Tron is not an average program. He's been ported from another system (the encom system he and Flynn liberated from the MPC) which might imply a certain adaptivity, and he was specifically programmed to be different from your average word processor or spreadsheet application. Clu's betrayal has not already turned him into Rinzler, but
merely corrupted his program, which he and Beck managed to cure at the finale of Uprising.
Since Uprising unfortunately got canceled, there is no way to tell how he became Rinzler, though
the appearance of Clu's fleet at the finale hints at an epic battle etc. or maybe even a heroic self-sacrfice (which would fit Legacy's ending...).
The last thing we see in Legacy is his original "Illumination" turning on. My interpretation is that the remainder or "Rinzler" died, while Tron finally fully "awoke".
So, is there hope? Well, given the movies ending where Flynn merged with Clu, which seemed to cause a significant explosion, chances are the (literally) resurfacing Tron still got wiped with the entire area or even Grid.
Too pessimistic? Well, Sam did a mysterious download at the end, and fortunately there is "Flynn lives" - yes, that's "The next day", a Teaser for the unfortunately canned Tron 3. The implication of that slogan and teaser seems to be Kevin Flynn survived merging with Clu, and that in turn might include the Grid and Tron. Or Sam downloaded a snapshot before Clu messed everything up... Maybe we'll know some day, maybe not...
