If there is even the tiniest inclination toward trying to draw in SF/lit readers who weren't around for wotmania's heyday, then I would say having a general Books/Lit board would make for a good "front porch" to welcome them. If this site is going to be all about people keeping in touch, then sure, a CMB with the occasional discussion might work.
Having been around back in 2000-2001 before wotmania had the Other Fantasy and later WoT MBs, I recall there being a lot less discussion of books (maybe as low as 5% of new posts) outside of WoT until OF came into being in October 2001. Then there were maybe 10-20 new threads a day even during slack periods.
So if you think there might be a glimmer of hope for permanently increased activity or that new people might join on occasion, I would say have two boards. If you think this site is predominantly for those who want to have "community" stuff and little else, then sure, have one board.
Je suis méchant.