I hadn't though about that but it's probably true, since most Cryptonight coins moved to the updated algo in order to get rid of the ASICs, therefore every ASIC that has been produced for the old algo is only usable on ETN and maybe a few other, less known coins. Thanks to that fact, we now have a pretty secure network.
You are more or less right about that one, just a little correction. ETN forked back as the 2nd biggest coin, biggest coin by market cap is still Bytecoin. The next big projects mineable by Asics on cryptonite are Sumo and Dero and Dynasty. Beside that there are about 35 smaller coins minable on crytonite. I was surprised my own to find out how many coins there are actually on the "old" cryptnite algo that didn't fork away.