If it's going to be a series it really does need someone to emerge as the foil for David Jason's Granville. That's what made the original series so successful. At the time, Jason wasn't a big name as such as his big break in Only Fools and Horses was just around the corner, but his face was well known. However, his partnership with Barker, the Arkwright/Granville relationship made the original series what it was. Often the dialogue in an OAH's episode would mostly be between these two well written characters, with occasional cameos from the rest. Still Open All Hours seemed at times like a series of sketches, partly to re-introduce the old characters, but also to get as much in as possible. There wasn't much of a story going on, maybe it needed longer than half hour, but it also needed that strong supporting character to carry it and I didn't see who that could be.
Will the young actor playing his son be up to that? Not sure based on the one episode. I did feel watching it that Rory Kinnear might have been good for the role of his son, although he would be older than James Baxter. Baxter is best known for Emmerdale, and doesn't have a comedy background. Kinnear was a pretty good foil to Count Arthur Strong in the TV show of the same name and will probably be taken up doing that anyway. He certainly would be more like Granville, which makes me think that as Baxter is a bit of a looker and doesn't have the same problems as Granville did with girls a story may emerge that he's not the father after all. Leroy was found on the doorstep (ho!ho!ho!), wouldn't it be a surprise if he was left there by the milkwoman who Granville had a thing for, because she knew he'd be taken care of?!
I think I would also have preferred to see the note that was supposed to go to Mavis end up with her sister. The ongoing story could then have been one of a tug of love between the two sisters and Granville. I still can't imagine the Black Widow Mrs Featherstone behaving the way she did, as she was quite stern and efficient, more of a Nora Batty type in the original. It's difficult to see her having any hidden passions for Granville or any man based on what she was like in the early series.