They have only one chance of publishing HL3, and I hope put in it the same love and care they put in 1 and 2.
I'd be very disappointed if they just released it just for the sake of releasing it.
But then why release Alyx as VR instead of HL3? What innovation did HL2 episodes 1 and 3 offer? Why are Valve releasing virtual card games today?
Half Life as a franchise is great. Gabe was right to start nearly from scratch on HL1 back in the day. But now, they've got everything they want so the hunger is gone.