It seems the Talosian method of luring in victims for their experiments wasn't too effective. Later Trek establishes that space is teeming with travelers, yet the best Talosians could ever do was one badly injured human female plus random specimen of species or cultures that for some reason or another were unsuited for their purposes.
Thus, if the Talosians willingly gave up on Pike (and perhaps far more importantly, Number One and Colt), one could surmise they really had abandoned all hope. Or alternatively, they had already achieved their goals and were playing make-believe. Even if we don't assume that Pike's original release was a mere illusion (and "The Menagerie" tries to argue that "The Cage" happened the way the audience saw it), and that Number One and Colt were really released as well, the Talosians might have clandestinely extracted from their new captives the biological components they needed for the servant species.
They didn't strike me as technologically savvy enough to bioengineer anything, though. A likelier scenario would be that they gave up on Pike in "The Cage" because they had a contingency plan going where a bunch of Talosians would come aboard Pike's ship unnoticed and take over the universe from there. For all we know, they then succeeded in that plan.
Timo Saloniemi