Generally speaking, yes, the cassette/shift lever chain is what's important here. The chains get narrower with 9, 10, 11 but the interior of the link doesn't change, so it will ride on the chainwheel without issues. But the back end, the cogset, that's where the narrower chain counts. And of course the shift levers need to have 8 clicks for 8 speeds, etc. Other than that, people have run 11 speed RD's on a 10 speed machine, no issue, and plenty of people have run 11 speed chainsets up front with an otherwise 10 speed drivetrain, no issue.