BTW in some sense, BTC is already inferior to many other newer blockchains
Factom is really a BTC/ETH app and inherits from the security of those 2 blockchains.
XEM would be better IF its security was equivalent to BTC which it has no chance.
I rearranged your post a little to analyze it. Can you clarify your argument as to why NEM isn't as secure as BTC and which alts you consider superior to BTC?
XEM or really any other blockchain today isn't as secure as BTC because the tiny size of their network make it vulnerable to things similar to 51% attack...
detractors of BTC would point out that a lot of BTC nodes are in China, which is not a good thing either.
on the specs side, XEM and many other blockchains are superior to BTC.... XMR has stronger anonymity, ETH has smart contracts, etc...