Those are not cryptocurrency categories(or at least,I shouldn't call them "cryptocurrency categories",crypto innovations is better) .Those are terms related to crypto/blockchain and offchain/sidechain solutions.
Do you think that Dapps,Lighting Network and IFOs are cryptocurrencies?
Each one of these crypto innovations has a lot of free room for growth and development.
Not all, but most of them are categories. OP didn't claim they were crypto currencies.
Just like there are different categories/industries you can choose to invest in when it comes to stocks (e.g. banking, automobile, telecom, pharmaceuticals, etc), you have that within the crypto market too (e.g. privacy coins, stable coins, Dapp platforms, Exchange tokens, etc).
Of course, there are coins that can rock multiple of these characteristics, but from an investor's perspective coins/projects are different categories/industries.
Coming back to OP's main question, I'm highly interested in seeing what will be built on top of Lightning. Tether plans to issue USDT on Lightning so it will be interesting to see how that will work out.