I would say that there are only downsides in going that way. If you take on a full rewrite you lose a lot: you can't show that you are incrementally better, yo

I would say that there are only downsides in going that way. If you take on a full rewrite you lose a lot: you can't show that you are incrementally better, you cannot show that it will be a good long term investment, you must rewrite even well maintained core parts that works fine, you don't get to improve the original engine with the good parts and essentially you get nothing in return. For a much better answer than mine: https://www.joelonsoftware.com/2000/04/06/things-you-should-never-do-part-i/ https://www.joelonsoftware.com/2000/04/06/things-you-should-...