There will likely be "easy solo merged mining" and likely merged mining will also eventually be easy for small pools too however there is no rush for anyone to push that.
If your intent is to mine BTC then NMC can be seen as a bonus. You mine 1 BTC you also get 0.x BTC free (after trading NMC for BTC). However that ratio DECREASES the more people (well technically hashing power) are merged mining.
When Merged mining first started it provides a roughly 140% bonus. Which means rather than earning 1 BTC you earned 2.4BTC in a given time period. Slowly that has decreased to less than 20% bonus right now. In 4 days when both NMC & BTC difficulty change it will be closer to a 10% bonus.
1 NMC is worth roughly ~0.02 BTC so if NMC hashing power (and thus difficulty) ever reached 100% of BTC hashing power that would mean the "NMC bonus" would be only about ~2% at current NMC pricing. Now I doubt NMC hashing power will ever be ~100% of BTC. Not every pool will implement it and some will never merge mine on philosophical reasons but that kinda provides a lower limit. Of course if price changes that would affect the "bonus" also.
You can estimate the NMC bonus by looking at
a) current difficulty ratios http://dot-bit.org/tools/nextDifficulty.php
b) current NMC price https://exchange.bitparking.com/main
BTC bonus = (NMC/BTC ratio)(NMC price in BTC)
Thus as of writing:
BTC "bonus" = (9.39)(0.018)
BTC "bonus" = 16.9% You get 16.9% more BTC by merge mining today than just solo mining (minus fees).