OK.....
First, this plan is a suggestion; Ofcom has not yet committed to it, and a decision on whether or not (let alone when) DVB-T2 will be introduced in the UK won't be taken until early next year.
No existing equipment will be obsolete until such time as there are no DVB-T MPEG2 transmissions, and there's no date set for that to happen, because there is no definite decision on whether or not to mandate DVB-T2 for HD on Freeview, let alone whether or not to migrate the whole of Freeview to HD using that standard.
So, any talk of obsolescence is somewhat jumping the gun.
As things stand, Ofcom is proposing that one mux be used to provide HD, using the DVB-T2 standard, from late 2009. Personally, I think this is pretty optimistic; there are a couple of reasons.
The main one is that the DVB-T2 standard isn't even at draft stage - that's expected by next spring. And people who know more than me about these things expect that mass production of equipment based on the yet-to-be-designed chips for this yet-to-be-published standard probably won't happen until 2010.
Second is that there will be some juggling of mux allocations necessary; if Ofcom decide that they're going to re-use a current commercial mux, then there's a lot of unpicking of contracts to do, and that could take a long time. If they take a BBC mux, then there's possibly less juggling, but doubtless a considerable amount of horsetrading.
When HD starts, there is no current equipment that will pick it up; no current equipment will work with DVB-T2, because it's not a finished standard. And if the BBC starts broadcasts using the current DVB-T standard next year, it will be using MPEG4/AVC anyway, so only one or two boxes (Evesham iPlayer HD, a Technomate, and not much more) will be able to receive it.
You will still be able to receive current broadcasts, and if the single HD mux is launched in 2009/2010, then it's probably possible for that to happen with no significant loss of other channels, though some +1s might go by the wayside, to free up space.
I think the 2017 timetable is even more optimistic for moving the whole of Freeview to DVB-T2 and HD than saying 2009 for a single mux, frankly. It's very ambitious, and much more likely that it'll be 2020 or later, in my view.
Even if it were 2017, that means any kit you buy now is going to be working for ten years; long before then, the hard drive, power supply, or something else is likely to have conked out.
The public will be informed of the plans - when they are actual plans, and not just outlines of things that might happen, depending on the development of new standards, and horsetrading between mux operators.
At the moment, despite the impression given by some news stores, there's nothing set in stone, and no decision made. Ofcom has said that they'll come to a decision in the spring. And even then, I doubt they'll lay out a formal timetable, since that will obviously depend very much on the ability of people to make equipment, if they decide to go for a new standard.
