I believe this plugin needs to be continued. Total Cache is overkill for some situations and won't even work in others. It throws out warnings about .htacess if you're on nginx or don't have access to apache's .htacess. If all a person wants to do is combine files with PHP and serve them from PHP, I don't think Total Cache can do the job.
For people on managed servers who want to combine files, I don't think there's even an option other than Autoptimize. I've been reviewing the code for Autoptimize and it definitely looks like everything is served dynamically from PHP so it doesn't depend on the HTTP server doing URL Rewrites. If I'm correct, this plugin is much needed. There is no alternative for people who don't want to or can't do URL Rewriting to cache files.
Can anyone correct me if I'm wrong on this?
If I'm right, I'd consider taking over development if I can get some assistance.