My main is a rogue.
I might be in the minority here, but the last thing i want is a dedicated healing soul. I like that there are some lines of demarcation between the callings.
I'm a dps monkey primarily, so i'd like a new DPS soul first and then a support soul.
As to what either would be, no clue.
If its DPS i woudl like to see something that has good meshing with other souls at low levels of investment (say, 5-20), but is also relevant at heavy investment (51+).
For support, it would be nice if there was some Bard Synergy, and tank synergy as a tertiary soul.
Honestly, i'd be thrilled if we got a new DPS soul and bard got the overhaul it needs.