Expensive is not a concern when you trade/use. (Expensive one is unfortunately the popular one and already reached to mass).
Banks and bitcoins are entire different concepts but with us to solve some financial needs. But, at some point if they work together, there will be more benefits to people. (Your bank will provide you a bitcoin debit card).
All colored coins/side chains are just a derivation of core bitcoin system. Adopting either one of them does not mean ignoring bitcoin.