IMHO we should not be afraid to throw parts of your system out every 6-8 months and rebuild it. Speed and Simplicity trumps everything! Also in 6-8 months, new technology, your improved experience, better clarity, etc. will help you design a better solution than what you can design today.
Just to be clear, I’m not suggesting that we do a sloppy job and rewrite the system because of sloppiness. I’m recommending, let’s solve today’s problem in the simplest, cleanest and most effective/efficient way. Let’s not pretend to know the future and build things based on that, because none of us know what the future looks like. Best we can do is guess the future, and we humans are not very good at it.