• HP1: 2019–2020
  • HP2: 2020–2021
  • RP1: 2023–2024

They can do two things:

№1. 2022–2023 webisodes bridging HP and RP. For example, Webisode 1 gives us more about Kim Sabi's family of renowned doctors. In Webisode 2, the HP characters were talking about an incident of a 1st year Resident who bit a fellow. In Webisode 3, the wedding preparations. In webisode 4, the disbandment of Hi-Boyz and his decision to be a doctor. And so on.

The webisodes will serve as a fun, "fan service", bridge. It is episodic (for those not familiar, episodic = no overall arc). And a webisode is usually 5–15 minutes long only.

2. 2021–2022 HP3. Instead of the usual format, it should be either a short series or a direct-to-disc or direct-to-OTT movie.

This is the only fitting timeline for any HP3 possibility. Why? Because the cameos in RP1 pretty much sealed everything that HP is over, there are less stories to tell.

If they set HP3 in 2023–2024 or 2024–2025, they'll have to deal with the cameos and movement of characters. Would HP be the same without Doctor Chuchu? Sure, they can push it to 2023–2024 and that's pretty much it. There's definitely no HP after 2024 as far as the original characters are concerned.

So, the best time period is 2021–2022. But since there won't be much stories to tell, and they'll end up rehashing the same patient stories too, it's better to keep it a short series. 6 episodes will do. Or, a movie. If they don't, they're risking tarnishing HP's overall rating. This is common in the West, later releases tarnished the overall rating of the franchise because they powers-that-be want to milk it when it already ended on a high note.