In all fairness Lobo, whilst you're right that it wouldn't be sustainable as is, Dani's point isn't a bad idea. You've got to look at the possibilities alongside the current realities. Yes the smaller Irish and Welsh sides couldn't afford it, but perhaps as soon as a Man Utd and Liverpool B side are thrown in their, it instantly incentivises things a lot more, although their would have to be a socialist approach to the division of wealth in the league. Sponsors would attain interest and back it I reckon, purely off the back of some top English sides and good young players being involved. The final hurdle then is the suggestion that the quality wouldn't be good enough for it to be worth sending a B-Team to compete. I suppose that has to be a gut call. Both Shamrock Rovers and TNS have had relative success in Europe (just getting there and few a Q Round or two) so you could suggest they may be up to it.
When you look at the actual problems surrounding the establishing of such a league, I believe it would be impossible, unless you could get Celtic and Rangers on board (and Celtic would probably sneer at playing B-Teams and attempt to use it as leverage to join the PL). There are too many problems facing such a league, however altruistic and pleasing an idea it is. I'm for it, but it doesn't look like it's at all sustainable or possible.
Here's your potentially sustainable league line-up (And even that is questionable) - Liverpool B, Everton B, Man City B, Man Utd B, TNS, Celtic, Rangers, Hearts, Hibs, Dundee United, Inverness Caledonian Thistle, Shamrock Rovers, Aberdeen, Linfield, Glentoran, Cardiff B, Swansea B, Wrexham. Obviously, some of these sides wouldn't want to compete or put out a B team, due to the inclement financial problems. I've also included Scottish clubs based on size rather than finish, which is why the likes of Aberdeen and Hearts are considered. I believe there's enough cumulative fans of those clubs to make a success of it. It'd certainly be a ground breaking system and would draw decent interest and sponsorship. I know I'd follow our B team and even attend as many games as I could.
I've simply tried to present and extremely optimistic roster that would constitute a sustainable model. All in all, it's probably too problematic, costly and complicated to get such a thing off the ground, but I've no doubt it would be supported better than the SPL or Welsh and Irish leagues, and players of the PL B teams would get a taste of real-game pressure and crowd atmosphere. I definitely think LFC and the Manc clubs could get crowds of 15,000 or more to games.
It's a good debate that I like a lot.