Lynw28 wrote:Do we know if they will still be useable in Legion against the new pets?
Short answer: We don't know yet what currency will be used in Legion.
Longer answer: For now, Pet Charms is still the currency used to purchase battlestones, pet treats, and even the new pets in Legion. But this could change at any time between now and the expansion's release.
Personally, I'm only casually collecting the charms these days. I'm not going out of my way to complete every daily; if there's a Menagerie battle that I find fun/interesting/quick I'll do it.
But other than that, I've slowed down my hoarding and will wait and see what updates, if any, there are for Pet Charms.