In the most recent TWIG, Burza confirmed that Renfri will be added to Gwent soon, likely in the next expansion. To be clear, my current campaign won't end until the day Renfri is actually added (not just revealed, but when the expac containing her actually drops). However, it's time to look to the future. I'll likely keep posting custom cards for a while, until it stops being fun for me. But I'll need a new character to campaign for, and there are a lot of interesting choices.
Some come to mind immediately:
Vigi the Loon
However, there might be other characters I haven't thought of yet as well. If you have a character you really want added to Gwent (not one of the above), comment below and explain why. Once I have enough responses, I'll put this to a vote.