What are you going to tax? PVs? Nicotine? PG? VG? If they get sold in a 7-11 then yes, you may get taxed. If you buy them off the internet like cigars, pipe
tobacco, snuff, shisha, etc... then there is really no way they can enforce taxes, or bans, or any of that stuff.
Cigarette smokers are used to getting tax. Pipe smokers have happily been avoiding those taxes for, well.. forever. I think e-cigs are certainly up and coming... but its going to be much harder to pass those sin taxes on a relatively safe product... without looking like a real ........
I think as e-cigs get more mainstream, and people realize what they mean for health and welfare, that its going to become very uncool to discourage their adoption as doing so means encouraging smokers to continue to smoke.