Problem being, we simply don't know how in demand DS9 and Voyager have been over the last decade. If there's been no real demand, CBS may not think that demand is going to grow going forward.
I just checked Space's listings here in Canada and Space is currently airing TNG and Voyager. And the last time that I had Space on my cable package (which was before the TNG Remaster) they were upconverting both TNG and Voyager to HD. At that time they were also airing TOS in it's 16:9 HD version. So I would assume that now that all of TNG is in HD, SPACE is probably paying a higher price per episode (unless CBS is still handling the sale of ad time, just like Paramount did back in the 80's and 90's, in which case both CBS & SPACE are able to charge more for the ad time), and they have most likely ditched the SD versions and are airing the HD versions. And out of all the shows that SPACE is currently airing, Voyager is probably the only show that I can see that is still Standard-Definition (Unless SPACE reruns old episodes of Doctor Who every now and then). (http://www.space.ca/Shows) Plus it's interesting how currently, Voyager currently holds the 5p.m. Eastern timeslot on the schedule (TNG currently holds the 4p.m. slot) every Monday to Friday; if I'm not mistaken that is when "Prime Time" is considered to start.
But there definitely is a market for CBS to remaster Voyager, and with DS9, it could be that they have interest, but because of it's status as a Standard-Definition show, that might be giving stations and advertisers "cold feet", especially if the cost to air the episodes is as high as they were when they were still in production (plus I remember that SPACE was still airing DS9 up til 2012, but then it was removed---I'm wondering if their contract on the series was up, and when they went to renew it, SPACE was hoping to get it for a little less than they had been paying, due to it being Standard-Definition---and that may be why DS9 is not airing anymore, the contracts for the stations to air it have expired, CBS wants a certain level of money, but stations and advertisers are refusing to pay it for a Standard Definition show).
In the U.S., Deep Space Nine hasn't aired since the Spike TV agreement expired in 2007 or 2008. Even then, it was rarely aired after Spike's first run through even though they had the exclusive rights to it and paid Paramount nearly a billion dollars for the rights to the 24th century series.
The stark reality may simply be that Deep Space Nine never gained any traction outside of a small, loyal fandom and the lackluster sales of TNG in HD likely was the nail in its already slim chances coffin.
Then the simple question for anyone broadcasting Star Trek is: how much Star Trek can be supported by OTA/cable audiences? Between TOS and TNG, there are already 250 episode ready for HD broadcast.
There's ALWAYS Trek on cable over here - even DS9 and Voyager get airtime.
A hi-def remaster of some sort will presumably be required to ensure their continued syndication saleability as standard-def dies off. No money will be spent on new CG or upgraded effects though. It'll just be upscaled and tweaked where no film is available.
I'd also be surprised if it was cost effective to release on disc...