If the only opportunities for advancement in your organisation beyond "senior developer" require a move into mgmt or team leadership, that will work against the stability of your teams. Seriously consider hands-on dev career paths with equivalent status and rewards.
@jasongorman This is the right thing for an organization to do, but I wouldn't expect it to make a lot of difference when it comes to retaining the best developers. For a lot of developers, the challenge of doing the development is the thing. Their passion is software development. Mentoring is rewarding, but it isn't the same thing as building something new. Life is not just about money and prestige.... Says the poor guy