In the beginning of the finale, Will is trying to resolve things with Lisa after her father lets his big secret slip. She's (understandably) upset because instead of trusting her the way she trusted him, he lied to her when he really didn't have to. She seems firm in her resolve that the relationship is over, but Will can't walk away and let things be done without letting her know that he's in love with her. When Lisa's resolve breaks, she drops a line that is so deceptively simple that most viewers may mistake it as a bit of throwaway dialogue: "You should know that I — we'll talk tomorrow."
Sadly, that tomorrow never comes because Will accidentally stands her up after his dad makes his unscheduled visit. But will that tomorrow come in Season 2? In case you've never seen a Tyler Perry sitcom or any other piece of entertainment which capitalizes on the "we'll talk about this later" trope, it seems unlikely that this thing Will should know is unimportant. And there's a context clue from earlier in the conversation which hints at what that thing might be. It's the part where Lisa talks about how she trusted him enough for them to be intimate, but she describes the experience in a flat tone of voice, rolls her eyes, and clearly has a look of regret on her face.
Granted, this is pure speculation, but is Lisa pregnant? If so, that could have some major implications for the show, not the least of which is setting "Bel-Air" apart as its own separate and distinct series from the source material. But we won't know for sure until next season.
