A few thoughts: 1. This will last years and never be finished 2. You're not starting from scratch. Not sure why you want advice on that. You're building somet

A few thoughts: 1. This will last years and never be finished 2. You're not starting from scratch. Not sure why you want advice on that. You're building something that needs to integrate with an existing pile of garbage. Most probably it'll be an absolute ball ache especially around data management. 3. Because of the above I'd just leave. Seriously. It'll be a mammoth task and if all you're getting is a junior salary it's probably not worth it 4. Just use laravel and architect things the laravel way. Using services as well MVC is fine, especially if you'll have an API too, but in general the less you diverge from the framework's usual approach, the more maintainable it'll be. 5. Of course there's a risk with a single DB. However if you architect for a single DB, there's nothing stopping you creating a dedicated one for critical clients. 6. Have you thought about leaving? Expect this to take several years and dominate all dev work until then (or lose steam at some point and be stuck with a mix of both). Ultimately this work adds little to no tangible value to customers and at some point management are likely to want to see new features being added again.