I hope that in Chapter IV (Post-50 content when it comes around) we get optional companions. Just think.

By 50, you have...

Your two tanks
Your healer
Your Melee DPS
Your ranged DPS

So why not have the option to say "forget you" to any new companions coming around? Lazy bum of a Bith trying to hitch a ride on your BH's ship? Heck no! Or maybe that potential Geonosian Companion insulted you one time too many? Go be eaten by a Rancor.

Sure, people might get upset, but at least people won't be losing their only healing companion.