Will be a long time before we see the senior sides tour the US & Canada.
Sorry should have clarified what I was saying a bit more.
There's certainly precedent for the home nations to tour places like US & Canada with fringe players during Lions tour years. Just not during the June window when the Lions tour happens. That's what is interesting to me about Scotland playing SA during the Lions tour.
Generally the teams that make up the Lions will tour in May (with possibly 1 game in early June depending on the availability of opponents) with their fringe team and then send an A side on tour in June. Alternately they do what England did and have the fringe players play home games rather than touring and send the A side on tour in June.
It's just very rare in modern times for home nations to tour during the Lions tour and certainly not against 1 of the big SH teams.
But I agree, as you said, it will be a long time before a full strength senior side tours either US or Canada.