Slicing isn't the thing that is broken, what is broken is that other crafting skills have to completely rely on other players to make equal profit.

So here is an idea:

Create a special NPC vendor (that would sit in GTN's) that will buy "player crafted only" items for 3/4 of their real worth.

That way player economy will still function, because if people want to charge full price or more (which they all do), they need to stick their items on the GTN first for a few days to have a try anyway. If they cannot shift their items they then can just vendor them, but for a price that would more than cover the price of crafting the item.

This will theoretically level out all skills because everyone would then be in profit. Whilst slicing may still be a much faster option, the other skills all have their own end game benefits that will balance out the the extra need time to become as rich as slicers.

And then you can let all the non-crafter/casuals happily slice their way across this game without nurfing it to oblivion. Because unless you forget Bioware you designed this game geared towards causal and somewhat solo play, force crafting is just going to scare/annoy all the casuals away.