Not so big a shift, but a big one coming
The BBC has been flogging tapes, CDs, DVDs, and the like for years, of any series they though they could sell Making the back catalogue available for download or streaming for a fee is just a shift of format.
That said, there is something quite curious about having the current content available for free (funded by subscription from those who choose to watch 'live') whilst making the back catalogue available by essentially the same means, but in return for a fee. It doesn't sound like a terribly sustainable way around to do things.