The new promotion system, will it hurt ambitious Soldiers?

I'm looking at this as a member of the Recruiting Command, but you can translate this in to squad leader/platoon sergeant instances. If the change is made to where you're an E-7 until 20 years, won't this take away the incentive to take on challenging roles? For instance, being a recruiting center commander is considered a "proponent challenging assignment". It's the most stressful, and is a direct leadership position, like a platoon sergeant, or in some cases, like a first sergeant. It's always been smiled at by promotion boards that you didn't take a break from being on the grind, on production, held accountable by the recruiting mission's numbers. The magic number is 3 years to run a large recruiting center to be eligible for special assignments and to be looked at as completing a good run in your leadership position. So after I completed 3 years, I was asked if I wanted a trainer position, operations, etc. I took on another recruiting center in order to continue to strive to make MSG. I consider myself an outstanding leader (pat on the back) and wouldn't feel right not being in a direct leadership position regardless of the stress that comes with it. If the promotion system is changed, what happens to Soldiers out there with the same drive and ambition? By the way, this is just a discussion, I'm not complaining nor will I ever stop being a leader based on the promotion system, I say again, discussion purposes only!