Here is my thoughts on why I think we will be able to ascend current gear in TTK and also will be getting more vault space. First. Why would damage reduction on specific weapons like the Gjallahorn be necessary if they didn't expect us to use it/them moving forward. It also makes me feel that the changes coming in patch 2.0, which drops when TTK drops, when they have stated that there will be more weapons in TTK than in vanilla, would indicate we will need the room to store all this new gear as well as old gear. Honestly, and not saying it's impossible, but I highly doubt at this point, seeing how vault space has literally been the biggest suggestion for Destiny, that Bungie would be so blind to not include it in TTK.