What if it's been kept secret and the climax of the story is the start of Monday's episode?

I doubt it, all 3 of Mark, Courtney and Grant have now left with no plans for any of them to return

What would be the point without Grant physically being present?

What the hell, the episode felt more like part 2 of a trilogy

I thought it wrapped things up quite well, Mark knows and Grant got his happy ending with Courtney

I think that next week Sharon will mention talking to Michelle. Mark will probably be angry at his mum for keeping the secret but hide it from his dad.

I'm not sure if this is something Michelle would do as I didn't watch back then, but maybe she will cut all ties from Sharon. The writers could do this so that there won't be any more terrible excuses for why Michelle can't turn up to important events.

No i think it's come to a stop now

He knows who his dad is and he seems to have no interest in having a relationship. That does happen in real life. I think i would of yawned if Mark had gotten out the car and ran after him and they had this big emotional scene where they declared one another as father and son. It would of felt like one of those shitty lifeitme or hallmark films from the states.