I think some balance needs to be added into these arguments here. Super League is a decent competition and England has some good development structures, is the NRL better than Super League? Arguably yes, but surely everyone who watches the NRL will agree the standard is better now than say 10 years ago?
The readmission of Souths, and the inclusion of the Titans, saw a short term reduction in playing standards in Australia as the talent was spread, we also saw a lot of very talented Australians heading overseas. Time has allowed the NRL and the clubs to reverse this, plus the improving Australian dollar, has helped result in the standard of the NRL being at quite a strong level.
Super League is at that point the NRL was 5-10 years ago, it has added two (soon to be three) teams in relatively short succession, which has forced talent to be spread, thus diluting the product for the short term. This short term pain will go a way in helping improve England and Super League's standards in the long term.
It has also lost some good players, but lets be realistic, the Australian dollar won't stay at it's current highs forever, there will be many exporters who hope it goes back down sometime in the near future, so it's likely those players will go back, and they'll help raise the standard of Super League, plus as raised before, by England increasing the playing pool, of professional players in their country, more quality will eventually come out.
New Zealand has gone a long way to improving by the fact there are more New Zealand eligible players playing professional Rugby League than ever before. They now have depth, something England needs to build on.
The UK just needs to keep on working at getting more and more Englishmen playing professional Rugby League. Particularly backs, their production line of forwards is excellent, but their backs, if there is ways players would be accelerated or something in their development, it would be useful.