5-10 years? In a company of what size, in what industry? For most "back-office" apps you're talking 2 years for the re-write just to see (almost) feature parity, and another year for the users to be trained and feel comfortable with it. If you were ripping and replacing a non-technical users go-to app every 5 years you'd have revolt.
We have 2 apps that are used for the same thing.... the original one and the rewritten one.
The rewritten one was coded up in C# over 3 years and isn't anywhere near as robust as the original one.
The original one was written in VB3 circa 1995 and dragged to VB6 where its stayed to this day.
Theres that much technical debt on the old app that the first change I made to it 5 years ago caused it to stop compiling because of the single line I added to a function which made it to big to compile.
If you work in a shop that has been around long enough to lose its training wheels and get a driving licence, then you have technical debt thats core functionality that everyone is scared of breaking.
