There is no list of platforms confirmed but since there was no "Only On Xbox One" text when the reveal trailer was played there is of course gonna be more platforms other then Xbox One. Since the fact that the last Tomb Raider was so successful on PC i would be really supriesd if its not released on PC.

Its also the same Developer and Publisher as there was on the last Tomb Raider so that makes it even more sure that its gonna be on PC. If i were to guess i think its gonna be released on Xbox One, PS4 and PC, im not so sure about the old consoles tho.