I think it may depend when the Tridents were cascaded out of London. I believe the ones that came out of the capital in 2006/2007 were not DDA'd (the early T-LLCs and the W-reg Alexanders which all left when First London lost route 7 on retender).
The rest of the T/V/W reg ones left London in 2009/2010, and I believe they were DDA'd, but don't quote me on this. I'd be surprised if they lasted much longer and made it into Olympia livery though, as they are 17 years old now.
As for the W-reg B7TLs, a large number have been DDA'd and refurbished over the last couple of years, including 30871-880 which were done up for the First takeover of Finglands in Manchester iirc. Whether any more will be done now, remains to be seen. It's hard to think these buses are now reaching the same ages of the WYPTE Atlanteans/Southampton Atlanteans/Leicester Dominators/Bristol Olympians they replaced at the turn of the century.