Tony hooked up with Betty.Kind of implied in the latter part of the game and would be a nice way to show Tony's Character Development.
After the ending, Kyle kept living in his car.The epilogue of the novel shows him, a month after everything's over, going to sleep in his car in the middle of the afternoon. He's either slacking off once again (in which case Ed isn't gonna be happy) or is having trouble finding a new home.
- So maybe Hotel Dusk and Last Window take place in a universe where Yomiel was never struck by the Temsik Meteorite. Cabanela and Jowd's real names are Brian Bradley and Kyle Hyde. Maybe Cabanela and Jowd are code names/radio callsigns, like Black Widow and Hawkeye from the Avengers. The two of them continued being friends/partners on the force, until one day Cabanela/Bradley was slated to go undercover to infiltrate Nile, and the rest is history. Because of Cabanela/Bradley turning traitor, Jowd/Kyle becomes obsessed with finding him and never meets/marries Alma. The reason Jowd/Kyle sees that black cat (Sissel) in the park is because it was never taken in by Yomiel and thus remained a stray.
In the game's closing Ambiguous Ending when Kyle anonymously donates the Scarlet Star to the Natural History Museum, he was setting up a trap for Nile.He knows that Nile would be after it, and would naturally break into the museum to get it. He sent the diamond there, then anonymously told the police that Condor are planning to strike the History museum, so that they'd catch them in the act. That, along with the evidence he gave to Frank to use against Condor, and Hugh Speck eventually being taken down by Frank, would give the police all they'd need to take down Nile for good.