I'm not sure that a character has to have a purpose.
Hope could simply be just another survivor. Her purpose could be to see to it that
Datu has some happiness seeing as how we might never know if he'll reach his family in the Philippines. Though the fact that she could regain her sight makes me think perhaps you are right. They made a very good point of not telling Hope about
Kalani's role as a spy and who knows what evidence her sight might bring into light.
As for
Michael telling them about Pinstripes, I'm very curious too. I'm actually hoping that
Saul and
Victor complete their mission of retrieving
Lizzy (and hopefully
Burt and
Angel too) so they can get reunited with Michael and the Ft. Irwin group. This house divided shit is pissing me off.
The Colony, Mallers, and all other survivors should quit feuding over an ant hill and reclaim the fucking world!