I'm just wondering if they'll remember to do the origin of the Valeyard when the time comes for 12 to regenerate into 13.
I believe once the Master described him as being somewhere between his 12th and final incarnation. If the regeneration limit ends up abolished or extended in someway, then that completely changes how far up ahead the Valeyard could be from.
I agree it would be nice to see the character explained, since those years provided some good childhood memories for me. But JNT era Doctor Who is typically maligned by fandom (to say nothing of public perception) and not as referenced by the New Series as the 70s and 60s - beyond Steven Moffat's charity skit declaration of love for the Fifth Doctor, that is.