I'm not worried about the DE captain slots disappearing, chances are those are a thing of the past for the most part anyway. What will suck is when guys who've been flying 1900s, Metros, Cargo Saabs, Cargo Brasilias, or stripped down Dash 8s for dynamic go to an outfit, and can't upgrade with their seniority because their time doesn't count. I may be a moot point, and yes, everyone is going to require time in the seat, but 1000hrs? C'mon, it doesn't take 1000 hrs to learn a jet and scheduled 121 rules. What is the difference between a guy flying a cargo saab in a 2 crew environment on adhoc trips and a guy doing the same thing on scheduled runs for Mesaba? I mean, hell, the ad hoc stuff is probably better experience - yet, it doesn't count any more.
A guy I know is an unbelievably good pilot. Flew cargo for years, got a 1900 type rating, and went to a cargo 121 operator to fly 737s. The guy was so good he upgraded in a years time (they upgrade based on a mix of seniority and merit there) with around 500hrs in type. This would not be possible under the new schema. Or, for a more seniority based method, imagine a guy flying for Empire with years and years of experience. He's been flying the caravan, and now has the seniority to hold an ATR captain position, he's motivated, talented, and capable, but he's not able toe even bid the run without sitting in the right seat for multiple years - probably to a guy who's junior to him. What about a cargo guy with oodles of hours in multi turbine airplanes who gets let go from his job because the company goes under. He goes to a regional so that he can stay close to home, but has to suffer both the paycut and a multi-year upgrade time with guys junior to him upgrading before him because those guys have that magic "time met by 121, 135.243a1, or 91k." It isn't right, and it isn't even logical. It's an arbitrary selection.
121 isn't that different from 135. I can't speak from operational experience, but I've read through the regs. It's just flying airplanes, dealing with dispatch, atc, and weather. Hell, in 135, a lot of companies don't have a very effective or usable dispatch office. Now, jet experience may be critical - everyone seems to say that, I'll let you know my take after flying one - but a guy moving from a 1900/Metro/Brasilia/Saab in the cargo world doesn't need 1000hrs of being SIC to succesfully and safely fly a Q400, DHC8, Saab, ATR, or a Brasilia and under the new laws it'd be required.
Will this make things safer? Hell yeah, and I'm glad it's going to be a reality. Is it a slap to the face of cargo guys, who could theoretically be flying the exact same equipment? You damn right it is.