You can check a 401k/retirement calculator to roughly figure out what you will have based on performance.
Retirement Calculators - CNNMoney
There are a lot of variables you've thrown out there too and don't forget, things change dramatically if you retire around a down year, who knows if another recession hits. Also you will not qualify for soc sec right away but that will pay something if it's still around. Finally, $10-20k a year difference can be quite substantial later, so I would not give up all ambition yet. In most careers, progression is a good sign.