Talon is trying to create new super-soldiers
In the Sierra hero trailer, Sierra mentions the place in Watchpoint: Grand Mesa that Talon is breaking in: the Naughton Vault.
Victoria Naughton, in the Overwatch lore, was an evolutionary biologist. She is, also, better known for having created the super soldier initiative, from which Soldier: 76 and Reaper gained their superhuman abilities (strength, stamina, faster healing, etc).
What's more, you'll notice that Emre was stealing a small case, which seems to be kept at a low temperature; which would indicate that it holds some kind of chemical or biological agent. I'm sure Moira will know what to do with it.
Thus, I think Talon's goal right now is to create new super-soldiers. Maybe one of the yet to be revealed heroes? Maybe to enhanced current talon agents (Vendetta, Moira, Sigma)?
What do you guys think?