Entrusting the future development of the network to just two exchanges, which could at any moment do the same as Poloniex, is in my opinion a risk that Maidsafe cannot afford.
If we add to that the fact that we left the USA people with no practical options, that simply leaves two real options. Add Maid to several reliable and globally accessible exchanges or opt for the Omni-ERC20 duality.
I don’t see any relation between the development of Fleming and the possibility of Omni->ERC20 conversion. @seneca already did a similar conversion with PDC and, besides some work on approving the conversions, it’s a simple process.