The ideal way to get TNG characters in the JJ-verse would have been, during Spock Prime's flashback in the first film, to have Picard, Geordi, Data and possibly even Worf, in the background as they outfitted the Jellyfish before Spock launched it. No lines, no big change from the scene as it was already done, just have some or all the characters from Countdown there in the background in place of the nondescript Vulcans we got. A simple nod to TNG fans.
Apart from that, why would we bring any TNG characters into the JJ-verse? More time travel, more alternate universe BS... no. It flies in the face of what the first film set out to do - reboot the universe.