The TPD, to be implemented in May 2016, replaces all national ecig regs in the EU, although states may make changes that are in effect stricter. Ecigs will become a regulated tobacco product in the EU.
A state may go further and declare them a medical product, but this is considered to be impossible to maintain in any country where the legal system works and where there is sufficient opposition (e.g. in northern Europe, but possibly not in southern Europe and especially south-eastern Europe); this has been overturned in every case challenged so far. So although the MHRA is very unlikely to be able to classify ecigs as medicines in the UK, they have been tasked with oversight of ecig consumer products, in a move stage-managed by pharma designed to allow them to eliminate any they don't want to succeed. That will most likely be anything not owned by Big T or Big P.
It is debatable whether some products will survive or not. Because of the financial pressures, and the well-understood benefits of having ecigs owned by the tobacco industry, I would expect that some of the tobacco firms' mini ecigs will get approval. Everything else will probably go, as it stands - meaning if the the TPD/art20 is transposed as-is, and interpreted as strictly as possible, which it will be.
A recent development is that TW UK have challenged the legality of the TPD's Article 20, which covers ecigs. The case will be heard at the ECJ in Strasbourg. Some people think the challenge has a good chance of success. There will be other challenges, no doubt, from other ecig vendors and from other EU countries.
If they don't succeed, then the legal ecig market in the UK will disappear, and the black market will take over. Not at first, of course: the MHRA will take a little time to get the enforcement procedures up and running. These will consist of setting up an ecig licensing department; getting the gov lawyers fully trained in the TPD provisions for banning ecigs and prosecuting vendors; requiring the specified documentation from vendors; rejecting the documentation when returned, and serving a notice to cease sales. Also a team of field enforcement officers; liaison procedures with local backup forces, e.g. police; police premises broaching teams; agreement on ability to call on armed police teams if required; postal services: inspection of imports; customs: blocking of imports, liaison with customs mobile enforcement teams.
All that takes time, and may not be completed for a year or so after May 2016. They will probably try and hit the ground running, but it takes a while to tie up all the loose ends. There will be a period from about mid-2016 to the end of 2017 when the legal market is being shut down, but the black market isn't fully operational yet, so products may be hard to buy.
The ecig websites will go to Norway, Switzerland etc, but they won't start to move until they have to, as site running expenses will take a big hike together with traffic dropping substantially at first - so the vendors won't move until they have to (all UK and EU ecig websites will be banned on the grounds of selling illegal products, together with cross-border advertising of ecigs, which is banned by the TPD).
On the other hand, TW may get Art20 struck down, and we go back on the merry-go-round.
