I'm not clear why some pundits are so worried about military bases on them, since the area is so small and you can't bury anything deep due to waterline. Anything exposed could be neutralized without too much trouble. The artificial islands give China the heavy footprint it previously didn't have, because it was a latecomer to the SCS land grab, and that's nothing to sneeze at, but military bases? Not very convincing.
Oh, I am sure they will base military assets in the SCS. IMHO, very little question of it.
The key will simply be what they do with them.
If they help control pirating and the international sea lanes, but otherwise maintain a relatively low profile, I do not think there would be anything about that to get too excited about.
The US is busy strengthening its military ties and help for Europe in Spain, Romania, Poland and elsewhere. In the region, the US has its own base in Guam and maintains other bases at the invite of the Japanese and the Koreans. It is once again increasing its presence in the Philippines. There is parity and balance in all of that...and it does not need to be, or necessarily portend, being confrontative.
In the end the key will be how Vietnam, Malaysia, the Philippines and Indonesia interact directly with the Chinese presence...and at a greater distance, how nations like Australia and India view it.
So, I do not think there is any doubt that there will be elements of the Chinese military there...and I do not think that anyone is going to try and stop them, other than protest statements perhaps.
But as time goes by and there is no confrontation, and particularly if China shows itself to not be seeking to grab more space in the SCS, or infringe on the economic activates of others there...and particularly if those forces, while keeping a low profile, assist in controlling and eradicating piracy in the area...then over time I expect it will simply come to be recognized as the new normal.
The US will continue to conduct FON exercises (albeit over time, less frequently)...and other nations may join in that. But as long as the heat stays down and it goes on with nothing untorward occurring...I expect things will proceed with that new normal.
At least I hope it will go that way.
...and quite frankly, short of someone doing something foolish and intentionally aggravating it, I think that is how it will go.