As the previous posters stated, this has no negative effect. If anything it will have a positive effect.
Your limit for comms went from something like 13.000 down to 50. You can only buy gear at exactly or below your level.
At best, you can keep 3 or 4 pieces of gear at level with that - the rest will come from the GTN or crafting.
Near the end, everyone will try to hold on as much as possible to their comms for the Makeb gear at 50.
Any overleveled char doing grey quests for "profit" is beyond help and won't have much negative effect to your sales on the GTN. (Doing any heroic content at any level takes time. Even a 50 will have to spend quite a bit of time running through "greys" on say Tatooine. In that time he could have easily completetd dailies or the Voss weekly which has a much, much bigger return on time invested.")
Since crafting those mods (by that i mean everything - mods, armorings, enhancements, barrels, crystlas) is fairly cheap for the majority of the level range, you shouldn't have a problem making a living with one of those professions.
My FP addicted chars have actually lost their main source of income with this change - they didn't craft before because it was cheaper and faster just "dump" the mods i've "outleveled" on the GTN. They can't afford to do that now anymore. Now they will have to craft stuff again - and get upset by the "undercut wars"