I don't see Markus using OOTP online to replace online leagues as they are now. I think he is trying to tap in to the fantasy market that wouldn't necessarily play via a PC software game.
I was also a little bummed to see this was still a planned part of the release. I am not sure how much focus it takes away from game development since it will use the same engine. However, the market for this type of set-up is already flooded. Most notably
Strat-o-Matic online who even has a partnership with Sporting News to get traffic to the game.
Others:
WhatIfSports
Sim Dynasty
SimYard
CSFBL
I researched this in the winter when Markus initially announced plans for OOTP online and came across many other sites like these. I figured he had scrapped the plans for the add on.