Yeah difficult to say who the backup LT would be with Hurst not around. I used to think the Ravens would normally go with the "best 5" meaning they'd kick a Guard or RT out to LT, but recently they've opted to pull from the bench. So its entirely possible that Ehringer or whoever wins the "swing tackle" job is the first guy in at either spot.
Depth at Tackle has been a concern of mine for several years now, and we've been generally pretty lucky with injuries there. Acknowledging though that its hard enough to find even competent Tackle player at a starting level, and we have two exceptional one's, so wishing for solid depth also is a bit unreasonable somewhat.
i think the philosophy changed so that the best 5 win in the preseason and training camp but once we're into the season it's about preserving chemistry as much as possible so that guys get to stay in their spots where possible