However, I think after reading the comments below that the scope of the project is to maintain backward compatibility with the agencies/authors of plugins in the Prestashop ecosystem.
What we were looking for is something that was trying to do new in the webshop ecosystem. Even I misjudged your "lack of MVC" comment below. My perception was that you were bringing together a lot of people from the Prestashop community and building something new with modern day best practices.
Using an ORM is the smallest of them. MVC is another. asset pipeline could have been a third.
But if you attempt any of this.. you will risk breaking backwards compatibility with any number of plugins out there. Which is why I'm doubtful you will try to do anything new. The way I see it is that you will maintain a bugfixed release of Prestashop 1.6 with incremental changes to support the plugin ecosystem out there.
Personally, I think you are aiming too low. You want to make something better than Prestashop 1.7 which is why your holy grail is to maintain backward compatibility and fix some plugins (like the Paypal one you talk about). But from what I have seen, your real competition is the Shopify of the world. Even Magento 2. Not sure if you have seen the docs, but Magento 2 has started adopting best practices out there:
1. composer for dependency management - http://devdocs.magento.com/guides/v2.0/install-gde/prereq/in...
2. database migrations - http://devdocs.magento.com/guides/v2.0/install-gde/install/c...