While the Q3s might be a more affordable option for first time adopters, many VR enthusiasts will have already picked up a Q3 and I'm not sure the specs of the 3s are that much better than the Q2 for Q2 owners to make the jump.
Having said all that, if a large percentage of Q2s have been borked by the latest V66 update (conspiracy theory tinfoil hats at the ready) then Q2 owners may go for the Q3s.