Sphere, I don't see how you can compare a failed league to a 1 off cup...
It goes to the mindset of the majority of people in this community. Whether it be the iCTF league, the 2v2 league not really taking off, new maps never getting thoroughly tested/feedbacked, or ideas like html's "Survivor assault" ages ago never getting a look in, it's always the same. In my experience, most people are only interested in playing the same core Assault gameplay: StdAS and team sizes as close to 6v6 as possible (every pug someone is '4v4+ only'
), with no new maps.
My worry is this. You will get some people signing up for something like DOM, but it won't be enough. And even if you manage to get 30+ people signing up, you still will have problems getting matches arranged, and getting people who signed to show up for matches.
Of course I could be wrong, but after seeing the organisers of new things + map makers (etc) getting their time wasted again and again, I would not like to be the one spending my time trying to arrange a DOM/CTF/whatever cup. In my eyes, the UTA community is an old dog that is simply unwilling to learn new tricks.
Disagreeing with you comparing DOM with ICTF.
ICTF is/was never a new thing. It was the well know CTF under annoying circumstances (called Insta).
Insta is way too onesided and gets pretty boring when your opponent has lower pings (yes even with zp) or/and are sniper fairys.
DOM is completly a different story. Even lower skilled teams have chances controlling points and even lower skilled players can do summn useful by capturing a point
The gamefeeling is a Battlefield-Light. Ofc without vehicles and without the annoying capture-waiting time.
They are very different indeed, and I could see a DOM cup being a lot of fun if people gave it a chance. However, when so many people are apathetic to learning new assault maps, what are the chances a large amount of people will learn a completely different gametype and all the new maps that come with it?
Also, like Torp alrdy pointed out, a league and a cup are two different pair of shoes. Mostly a cup gain much more interest than a league, caused by knowing that it's just a short temporary event.
I agree with this, people would be more willing to try playing a different gametype in a cup format compared to a league one. Would it still generate enough interest though for an entire cup of non-Assault gameplay?
Disclaimer: I am not trying to start a fight or be dismissive, I am in a way just playing the devil's advocate. I think it's great that someone is trying to start another cup, and I would be first in line to sign up for it, whatever the setup 
pete
