Guild marks didn't do anything other than unlock class abilities, and all of those abiltiies were removed, thereby negating any need for them. Beyond that, they also showed up randomly as rewards instead of gil, when most people would have rather had gil instead. Thus, guild marks were both pointless and getting in the way.
I've already cut my inventory down from near max to 150 or so. Your equipment, both your main equipment and the equipment in sets will no longer be in your inventory- so that's a significant number of inventory spaces freed. Like me, you very likely have a lot of stuff in your inventory that you really don't immediately need at any given time. You'll be able to pare it down. Beyond that, we'll most likely have bags for additional storage later, and free companies will supposedly have a bank. You'll also have a delivery system and you could send yourself stuff to save space, and you can also have 8 characters on a server if you are a legacy member, so you can also mule a lot of stuff.
