Absolutely. Many carriers are reconfiguring their 777s to 3-4-3 (10-abreast) seating where 3-3-3 (9-abreast) was the norm, and the 787 was designed to be outfitted 2-4-2 (8-abreast) but most carriers are choosing to put 3-3-3 in them.

Given that the airframe doesn't stretch that extra space has only two places to come out of: the seats and the aisles. And since you can't squeeze the aisles beyond a certain point, the seats have to necessarily shrink too.

All of this because we want slightly lower fares.