I voted yes for dramatic effect. I think in terms of media portrayal, crowd numbers, finances and player crossovers I think Union will and perhaps already is totally eclipsing League. In this country at least Union has been on the march since they formally admitted professionalism. They get bigger TV deals, their international game is vibrant and exciting and something everyone in league is extremely jealous of whether they care to admit it or not.
Of course in other countries the code isn't faring all that well. Australia seems content with League and AFL being the better sports and the NRL is IMO the benchmark rugby competition in the world in terms of the quality of the individuals playing it. It doesn't seem to be Union making the in roads it seems to be soccer over there.
Will Union being bigger stop league existing? Well no, of course not. F1 existing and being far, far, far greater doesn't stop the tiny motorsports existing and I'm sure League can mill along pretty much as it is. Even without a TV deal they could run a semi professional league. The main problems League has are money and the calibre of the people associated with it. The governing body in the UK for RL is the most embarassing collection of people you are ever likely to meet. Not one of them has any marketing ability or commercial acumen. Add that to the lack of money in the game as a whole and it's not a good recipe. We've been professional for decades and have reached 2011 with a gaggle of semi-decent clubs, 1 viable European club and that is it. Half of Super League and the entire NL system is made up of clubs that shouldn't really exist as they have no fan base to speak of.
The major difference is how well run Union is. It has management of a level league cannot even dream of. Their decision makers and publicists and their media controlling expertise is just brilliant. They could sell snow to an eskimo. Union will IMO continue to grow and evolve and will probably be football's main rival within 20 years IMO. They seem to be slowly bringing the US in, almost all US colleges now play Union. It's only a matter of time before that develops.