Devlin may never acknowledge Gwen as a mom, or he may acknowledge her as a mom. What we saw of him (loyalty to his father until he showed he didn't care about him) tells me he won't. As for Devlin's mom, I doubt she's dead. However, Kevin spending decades in the Null Void probably made her think he was dead.
Devlin is too old to acknowledge Gwen as his new mother, although that in no way means he doesn't love her. He can love her as a step-mother but not as a mother. The more interesting is Kevin and Devlin's relationship. He can probably forgive since he knows how it's like to be taken over by his genes but he will never forget.
Yah. Another question is that people are confused that why Gwen did not use her anodite powers in OS. Well my theory is that Future Gwen did not want to reveal to young Gwen about anodites and so that is why?