Garchomp being banned doesn't affect the viability of Salamence in any way. Salamence is still the most powerful non-Uber user of Draco Meteor, giving him a niche that Garchomp could never fill. Salamence's Intimidate makes a bulky set including Dragon Dance and Roost very viable, as he can wall many things lacking an ice attack very effectively while statting up.
Let's say I like Luvdisc (I don't, but let's use it as an example). I can't say "Yay, Garchomp's banning means I can use Luvdisc more!" Garchomp's status in the metagame doesn't magically make Luvdisc better, or make it fill a niche that Garchomp once held. Garchomp and Salamence were strong for two separate reasons, and there are many people who think that Salamence is in many ways better than Garchomp. (Access to Dragon Dance, better Special Attack, Intimidate) No matter what, you can use Salamence just as much as you wanted. I use Salamence as a strong special attacker, and Garchomp's removal doesn't make that any different.