I'm going to be upgrading my 2x10 drivetrain to a Shimano XT 1x12.
While my current crankset's Q-Factor is 175mm and the chainline is 48.8mm (non-boost), the Shimano XT 1x12 has a Q-Factor of 172mm and the chainline is 52mm.
What, if any, affect will this have on my bike?
Is it possible to update to a 1x12 drivetrain and retain a 49mm chainline?
You can just put a narrow-wide chainring on your existing cranks, and have your choice of chain line.
The 10sp double chainline is measured inbetween the chainrings so its imaginary,the big ring will be about 53mm chainline so depending on your cranks you could use chainring spacers to bring it in 2 or 3mm, XT 12sp chainlines now start at 52mm and can't be reduced.
If using a shimano 12sp hg+ chain, not all aftermarket rings play well with this chain, burgtec and superstar do work, other companies make specific rings for shimano 12sp but they're pricey though.