I believe that code-base no matter how well written are doomed to the fate of eventual obsolescence. No matter how well the code is constructed, there are bound to be unforeseen edge cases that can have a minor or major impact on your code. If your business decides to take the code to a whole different level, you might need additional functionality that the code-base didn’t account for. “The best laid plans of mice and men oft go astray”. Businesses need to plan for this case, and allocate the resources accordingly.
It’s possible for your code to absolutely perfect and NEVER EVER require change. You might even conclude it might be a Microsoft only thing, but think about it this way. How often has Microsoft, Apple, Linux, Facebook, Myspace, and Google changed their code? Quite often, it’s almost like every few years, some major change occurs. Windows XP was recoded into Vista, and Windows 7 was Windows completely recoded from the grown up. Changin not only the look, but the security and functionality.
Code changes because they business requirement changes. Business requirements change because the customer’s demands change. Time changes a lot of things. So you have to ponder, if your code-base is an exception to the rule. Chances are, it’s not. If you don’t plan for the team to completely recode the code-base every few years, then you’re going to force yourself into an immobile position where your customer’s demands have changed, but your business can’t respond to accommodate it.
With each new core product system, you should keep track of how long it took to develop it, make sure it’s well documented, and budget some time in the future to reallocate this amount of time to reinventing it. Yes, reinventing. Is this a direct violation of the DRY principle (Do not Repeat Yourself)? No. If it was exactly the same product, sure, it’s a violation, but since you’ve introduced new parameters, the no. Do you use the same method to do single-digit against single-digit multiplication as you do double-digit vs. double-digit, triple-digit and so on? No. Code should be no exception, plan accordingly, or face some interesting crossroads in the lifetime of your business.