If the RCMP gets out of contract policing, they should get out entirely. There would be no critical mass of personnel in the various provinces to maintain specialties such as tactical, aviation, major case management, etc. To me this would argue towards either a provincial service or at the very least large regional ones. Alternatively, they would have to enter into some kind of contract arrangement with a large municipal service. The only exception might be forensic labs. They are a civilian heavy/exclusive behind-to-scenes role, but certainly nothing front line.
In regards to FN policing, Ontario is light years away from where it was when I did it, but there are still a lot of gaps. Most of Ontario is covered by a combination of treaty-based FN services, a few larger stand-alones and a few smaller territories that remain policed by the OPP. The treaty-based services are essentially regional services with members deployed to their various individual communities. Federal and provincial funding remains an issue, but even if it were not, they still need the support of the OPP for specialty services because of their deployed nature.
I don't know the current numbers but for a long time, a large proportion of FN members were not Aboriginal. When hiring by other services was slow, the glut of 'police foundations' grads were signing on with the FN services. I don't know what it's like now with everybody hiring but I get the sense the depth of suitable FN candidates has improved. There is still a weakness of suitable candidates from many of the FNs themselves. Most isolated communities consist or only a handful of families and there is often a reluctance to 'police one's own'.
Providing deployed emergency services is disproportionately expensive compared to areas of higher population density. This is made even worse when it is a dispersed collection of small, isolated communities. Funding issues aside, I would think all of the federal territories would be heavily challenged to sustain viable police services on their own.
You’re taking an extremely narrow view of it predicated on simply putting people out in the field to do 911 style field police work, and as a result your conclusion that older hires are a poor investment is incorrect. The reality of complex modern multi jurisdictional and interdisciplinary investigations is you need and want a mix of different skills, experiences, and backgrounds. Most police can retire with a pension with 25 years of service. Nothing wrong with taking a 30 year old who did six years with CAF then 5 with CBSA. Or maybe someone with a few years driving trucks interprovincially, or working casino security, or capital market investor relations, or as an intelligence analyst (I have worked with all of these people).
There is not one single ideal recruit profile. Policing isn’t a clone army. The person who joins and would be a good fit to post for Fort Saskbertoba for general duty policing may not have the same CV as someone who comes in and is a good fit for an integrated market enforcement unit, or a national security focused unit. There are multiple intertwining or cross-crossing career paths that are all equally valid in this overall profession. And yes that can start with a wide variety of different recruits.
I don't know how many parallels there are with the RCMP, but the OPP has faced a number of challenges staffing small northern detachments (I get that 'northern' has a different context, the OPP only has one detachment that doesn't have a road to it). Back in the day, staffing was a combination of recruits, voluntary transfers, punishment transfers and 'administrative' (involuntary) transfers. Punishment posting went out the window years ago and I'll bet there hasn't been an administrative transfer in 20 years. Voluntary transfers are down for whatever social/family/lifestyle reasons, which largely leaves recruits. It was not unusual to have an entire small detachment under 5 or 6 years in service, with a training officer being just off probation themselves. As anyone who has done it knows, isolated policing has its own rules, and when you learn those ground rules as a recruit, from a just-former recruit coach officer, they don't often translate well when they eventually move to the 'normal' world.
Even with incentive allowances that can reach into five figures, staffing remains a challenge. One solution has been to close a number of smaller detachments and police them from further afield. They maintain they are providing the same level of service. I disagree, but they never asked for my opinion.