One issue with plugins for things like WordPress is that they need updated for almost every release...
That being said, I'm curious about packages in Laravel... Will 4.2 packages work with 4.3? Will they need to be updated or require that the Legacy Provider be used?
I think some packages may work while other ones won't depending on what they do and how tied to L4.2 they are. Interfaces apparently are an issue https://github.com/laravel/framework/issues/5551
Also if any package is using the HTML or Form aliases it won't work until we use composer to pull in Illuminate/Html and add the aliases.https://github.com/laravel/framework/issues/5557. packages will need to either require it as a package dependency or include instructions for installation. I hope Illuminate/Html is added back since it also breaks link_to_route()