I'm not completely sure I understand the question, but let me take a stab at it.
The DTV conversion is a change of transmission standards. It does not require stations to change the way they produce programming internally. Stations that are still gathering news on analog videotape can keep doing so; the video would be played out of analog videotape machines and fed into the control room, then sent to master control (which can be either analog or digital, depending on the station). It can even be sent over an analog studio-transmitter link to the transmitter to be converted into digital standard-def for transmission.
There are no requirements that stations broadcasting digitally do so in high definition.
So for station archives, nothing really changes. Many stations that had news departments back in the film era (1950s-late 1970s) got rid of their film later on; some, like that from WGR-TV and WBEN-TV in Buffalo, ended up in good hands - the Buffalo Broadcasters, in this case, who are working to restore and digitize it. Others simply trashed their film, sadly. Most of the stations that still have their film in a basement or storage room no longer have the ability to view it in house. My local WROC-TV is an exception; it maintains a working film chain and continues to use excerpts from old film, as needed, simply by playing out from the film chain into whatever format they're currently using for news production. Most every station still has the ability to dub from older analog videotape formats (3/4" U-Matic, Betacam, even the older 1" reels) to current formats as well - although, ironically, the videotape from the start of the field-video era (late 1970s-80s) hasn't always held up as well as the film.
More recently, many stations have converted to various digital formats for shooting video in the field and editing it in-house. That's not even anything new. When I started doing TV here in Rochester (at R News, the cable news channel), they were in the process of moving from analog S-VHS to digital DVC Pro in the field - and that was way back in 1997! Today, I think three of the stations in town use DVC Pro, while others are using newer solid-state digital recorders.
If you're asking whether stations will convert their entire archives from film and analog videotape to digital formats, I'd say that's extremely unlikely - you're talking tens of thousands of hours of video at some stations, and as long as it's still playable in the original format, it can easily be transferred to newer formats (including upconversion to HD for stations that produce local material in HD) as it's needed.