Assuming David stays long term, it is bound to happen at some stage but I think they will wait awhile.
For all his faults, David is a faithful soul and he really did love Kylie. He didn't get with anybody when Kylie cheated on him with his brother, or when she left him, seemingly for good so i can't see him doing it anytime soon following her death with kids to concentrate on.
But in time, maybe a couple of years, they will pair him with somebody - probably a new character.
I do agree - it seemed really random when David came back from holiday having hooked up with a girl who turned out to be Becky's sister. But it was a really successful pairing. The actors just clicked and the writers did them proud, including keeping them faithful (bar kylie's one mistake with David), in some ways 'boring' re looking after the kids but still sparky.