What would make it hard to return to Canada after twenty years?
Housing affordability: Canadian prices have skyrocketed in the past 10-20 years and have increased much more than the US.
Cost of living: it’s generally higher in Canada.
Where to live: there is much more variety in the US. For instance, there are few “quaint small towns” in Canada in comparison. The American small town/city with a historic Main Street has survived, whereas it’s a fast-vanishing thing in Canada. Much of Canada is starting to look the same in terms of the built environment and urban planning.
Access to healthcare: Canada has universal healthcare, and the system kicks in if something serious happens. But for anything not at that level, there are serious issues. For instance, depending on where you live it can be hard to find a primary care doctor. There are waiting lists for many procedures, for imaging, etc. If you have an upper middle class type situation in the US your access to health care is much, much better. I can often get in to see my doctor within 24h.
Employment opportunities: it’s much better nowadays, but the US is still the place to be in terms of variety of work and compensation.
And finally, it’s hard to leave anywhere after decades - you get used to your life and your community. Canada will always be my homeland, but it’s starting to feel a bit alien to me, in subtle ways.
Canada has changed over the past 15 years and you can’t step into the same river twice.