What comes next in the series D2G, G4K, J8O, M16S?

Three things move together. The opening letters D 4, G 7, J 10, M 13 go on by three, so the next is 16, which is P. The numbers 2, 4, 8, 16 double, so the next is 32. The closing letters G 7, K 11, O 15, S 19 go on by four, so the next is 23, which is W. That gives P32W. Advancing the closing letter by only three gives P32V; adding 14 to the number instead of doubling it gives P30W; advancing the opening letter by four gives Q32W.