Your example is much smaller than what people are usually talking about in terms of big-bang rewrites. So maybe you will be successful. Even so, you're better

Your example is much smaller than what people are usually talking about in terms of big-bang rewrites. So maybe you will be successful. Even so, you're better off doing a step-by-step rewrite, where the new stuff and the old stuff coexists in a single application. That way your users can continue getting incremental benefits over time even if the rewrite takes dramatically longer than you're optimistic estimate. If you can't figure out how to manage the complexity of a piecemeal rewrite, consider that you may not actually understand the system well enough to avoid making version 2 just as bad as version 1. Most people overestimate their ability to act differently than they've acted in the past. It's like the unjustified optimism of a New Year's resolution that this time you're actually going to exercise every day. To get a better result than last time, you need to impose some very clear rules on yourself that cause you to work differently.