It wouldn't be tremendously difficult to change the name of /ub/ to /fitlit/, the worst thing likely to happen is it might break a few cross links from posts on other boards. However, I'll echo the sentiment that such a change is unlikely to have much of an effect.
>advertising
An advertising campaign would require money, and while I wouldn't necessarily be opposed to spending a few bucks to improve site traffic, I don't see this having much effect either. If we wanted to draw traffic to a new /fitlit/ board, the logical places to advertise would be /fit/ and /lit/. /lit/ is one of the few comfy boards left on 4chan, mainly because they don't get a ton of traffic either. Mods, trolls and spambots mostly leave it alone; the userbase there has no real incentive to migrate anywhere. /fit/ I don't know that much about, but they seem to have their own niche culture, and they are also unlikely to want to migrate anywhere. They also strike me as a board that would have a high concentration of users likely to be hostile to bronies/horsefuckers.
Apart from those two boards, the only other places that make sense for targeted campaigns are /mlp/ and /pol/. /mlp/ is well aware of us at this point, and anyone who wants to migrate and/or crosspost here has already done so. /pol/ seems to be mostly bot and shill traffic these days.
>If we're looking for April 1st '17 posters, then a complete rebrand would be necessary.
If we were looking for April 1st '17 posters, the time to do it would have been around April 2017. I'm sure many anons fondly remember the event as a fun couple of days of shitposting, but most have long since gone back to their respective homeboards and probably won't be interested in a reboot of the concept.
>fuck /a/, fuck /cyb/, fuck /intr/, and fuck /sp/ (negotiable).
/a/ probably gets more traffic than /ub/ at this point, and I doubt rebranding it to /fitlit/ would do much to change that. Every chan and altchan has an /a/ board, so it's not much of a draw for outsiders. At the same time, there is some crossover between anime fans and pony fans, and /a/ is really the only board where anime discussions can take place.
/cyb/ never made a ton of sense to begin with; it was a pet project of Atlas's. Most of its threads would merge pretty seamlessly into /vx/. Also, when I went to skim through it, I noticed a couple of month-old advertising spam posts that we apparently missed; that one's on me, sorry. But it seems to buttress the argument that nobody pays much attention to /cyb/ and it could probably be deleted or merged into /vx/ at no huge loss.
/1ntr/ is a separate community whose board we host due to an agreement made by Atlas and their admin way back when. They don't post much, but at the same time they aren't hurting anything. It would be kind of a dick move to just yank their board out from under them for no good reason.
/sp/ I'm somewhat biased on, but I will point out that it's probably the highest-traffic board after /mlpol/ (apart from /vx/ I guess, but that's due to the RP threads). It also provides people an outlet if they want to shitpost, and makes it easier to maintain a higher standard of quality on the mainboard. That said, the concept is basically just /b/ under a different name, and it probably confuses outsiders who don't understand the joke.
Anyway, I guess I don't care that much either way. I can't speak for the rest of staff, but if you guys really want to rebrand /ub/ I don't have any serious objections, but I wouldn't expect it to have much of an effect.