There will be an aftermarket company making replacement batteries. Assuming Apple stops making them, which is unlikely for at least 5 years.
I have a 2-3 year old Compaq laptop still running strong except for the non charging battery.
So your Compaq with a non-charging battery is "still running strong" after two years, but a Mac with a non-charging battery is "useless" and a "boat anchor"? WHY does your Compaq have a non-charging battery? Wasn't it covered by warranty? Aren't they incredibly cheap and easy to replace?
Difference is your Apple with proprietary battery will cost $3000. I bought my Compaq for under $450 after rebates and promo codes in May of 2007. A replacement battery for mine will cost $130 from Compaq and considerably less from import aftermarket companies that sell on Ebay which I am leery to trust. I am biding my time for the next gen Windows 7 laptops to finally upgrade.