If they were lost, it'd be the exact same situation that happened to Babylon 5, and which is preventing that series from getting an HD upgrade -- essentially, the original CGI files created way back in the mid-'90s were dumped out of memory and lost.
What this means is that Warner Bros. will have to spent a huge amount of money to create brand-new visual FX from scratch if they ever want to release B5 on Blu-Ray.
But at least they wouldn't look so fake. I loved B5 but thats the one thing I always hated about it.. The CGI was cool. But looked 100% fake. Great for the 90's Not so much today.