That was the original plan. Unfortunately it's been indefinitely prolonged because of the various issues at Northern and I'd be surprised if Covid hasn't finished the entire idea off
I'd say there's a reasonable chance of you getting your hourly service back, but a near-zero chance of the proposed frequency doubling this side of HS2 opening. There are some much busier lines than yourss which don't have a 20 minute service yet so I'm almost certain that won't happen in the forseeable future, and if I was in charge of the planning I'd certainly be prioritising a recast to give Heaton Chapel & Levenshulme a proper clockface service over sending an extra train down the Mid Cheshire.
I think that once the crisis is over and people come back to the railway for day to day travel, half hourly is a sensible aspiration for a decent usable local service, particularly for an area such as mid-cheshire with a good string of well-to-do towns.

