UK should field a single Great Britain team permanently, instead of carrying on with England, Wales and Scotland. Scotland, Wales rarely if ever qualify for international competitions, so they are depriving their talented players the oppotunity to play tournament football, the harsh truth is that there is little point in the existance of these teams other than nationalism. The benefit for England would be that a GB team would have that bit more depth when it comes to tournament football, it is becoming more and more prevelent that Premier League players get injured, considering all the injuries England had and the lack of quality replacements, how much better would the England have been at Euro 2012 with players like Gareth Bale and Aaron Ramsey? These players are wasted playing for Wales, they should be playing in World cups and European Championships. Unfortunately there is too much petty nationalism which will always prevent this from ever happening
I foresee another fiasco like the bickering and squabbling prior to the 2012 Olympics should such a proposition ever be seriously put forward.
The thing is, although it is Scotland, Wales and Northern Irish players who lose out on playing international tournament football, they would rather die than line up in the same team with Englishmen and sing God Save The Queen before kick off (it's difficult enough to get the Englishmen to do that with any conviction or pride). Most of them would rather garrotte themselves on the pitch than allow that to happen.
Perhaps the OP is motivated in putting this idea forward due to England's dismal performance in Brazil and the prospect of another 48 "years of hurt" (and more..!!)
But I feel that, for better or worse, we are who we are and we just have to get used to the fact that England and Scotland are now third level footballing nations and Wales and Northern Ireland, whilst ranking above San Marino and Luxembourg, there isn't much in it.
As for the quality players those countries produce, well, quite often it is found that the player may have been born in England or has at least one English parent, or qualifies to play for England by residency, but CHOOSES to play for Wales (ditto Scotland and Northern Ireland), in the knowledge that his team of choice is likely to fare poorly in competitive football.
He could have stuck it out and chanced his arm on being selected for England, but went for the relatively soft option of being an automatic choice for the "lesser" (for want of a better word) nation. If he misses out on the big tournaments, it will probably be down to his lack of ambition and belief in his ability to rise to the top, rather than the failings of the international system.
Things are unlikely to change. England, Scotland, Northern Ireland, Wales. That's how it is, that's how I see it staying, and for some time too.