I enjoy metaphysics and epistemology, but my query is very practical.

Like many in the UK, I have a large collection of videos. In
particular, a complete set of StarTrek: TNG, and all bar a few of the
last series DS9 and Voyager. I am now worried that I wont be able to
enjoy them in future years.

The options seem to be: buy a swanky video player from a big company,
and hope they keep servicing it into my dotage. Sell my video
collection and buy it on DVD (and hope this format lasts til my
dotage). Is there an option to download videos to your hard-drive?
This might be favourite, as you can (so far) usually convert this
year's Microsoft format to the next, before you switch O/S.

Advise, please.

I wouldn't worry about this too much. It will be a long time before
you will not be able to buy an old VCR very cheap.
Take a look at the amount of $20 or less 8 track stereos available on
ebay!: http://search.ebay.com/search/search.dll?cgiurl=http%3A%2F%2Fcgi.ebay.com%2Fws%2F&krd=1&from=R8&MfcISAPICommand=GetResult&ht=1&SortProperty=MetaEndSort&query=8+track+stereo
This is a 30+ year old technology.

And way before the time that VCR's become completely obsolete, you
will be able to have access/download pretty much any television show
ever made as well as all new releases for a small fee:

"In the not-too-distant future, it will seem absurd to consumers that,
when they wanted to watch a movie, they used to have to get in their
cars, drive to a store, rent a physical object that they had to shove
into a machine and then take it back to the store." 
http://www.washingtonpost.com/ac2/wp-dyn/A20623-2002Jun20?language=printer

Right now in some areas there is a new cable service that offers an
extensive archive of old television shows that visitors can watch at
any time. Access to this archive is at a fixed monthly price. I'm not
sure if the specific shows you've mentioned are available on there yet
(probably yes), but the trend is clear and that is that VCR's, DVD's
and other removable media will be replaced with on demand
transmitted/downloaded media and this in the not distant future.

A good look at the future of television shows and movies is iTunes:
http://reviews.cnet.com/Apple_iTunes_Music_Store/4505-5_7-21220230.html
This allows users to buy individual songs at $.99 each from an archive
of over 200,000 songs and growing. You will see this model be
developed across the media spectrum: tv shows, movies,
games...everything will be available on an on-demand basis. I believe
that the trend will be that you will pay for new releases
song/show/movie, but you will be able to pay a monthly fee to get
access to a huge archive of old media.

So don't worry. You will be able to play your tapes on your VCR for a
good long while yet and by then the shows that you have will certainly
be available in the future at a much cheaper price than buying them
now on DVD. In fact, in the future they will probably be available
with your basic cable tv subscription.

I hope that this helps to answer your question. If you need any
clarification please feel free to ask before rating the question.

Thank you!
-shiva777

other articles I came across in my research:
http://www.azcentral.com/ent/pop/articles/0418vcrdemise18.html
http://www.cbc.ca/stories/2002/07/02/Consumers/DVDsales_020702

Search strategy:
"video players obsolete"
"vcr's obsolete"
"archive of every television show"
"archive of every tv show"
"itunes review"

At the very least, you can transfer VHS tapes to DVD using one of the
new generation of DVD recorders. But as shiva pointed out, the total
demise of the format is far into the future. Consider vinyl records.
Dead once & for all? Not quite; there are in fact still some small
quantities of vinyl pressed for many artist's recordings. Hard to
find, but still extant.

-Mark Martin

Answer is to buy a half dozen vcr players, pack them up carefully and
store them for the future...