Personally, I don't envisage e-cigs "catching on" BIG style in the long-term. ... they're weirsh, tasteless things - which most definitely cannot replace the satisfaction to be derived from proper tobacco products.

Admittedly ... ... I've partially sampled only one - bought in the local Poundland store - but it offered me so little satisfaction that it's lain (otherwise) untouched in a kitchen cupboard for months now!