Scaled Agile Framework offers a nice collection of Agile best practices. The Big Picture helps to visualize different concepts and ways of connecting them together. But one thing has always bothered me: there's no Customer in the picture. That's why I was positively surprised to read that the new version 4.0 will include also this one missing part.
I guess SAFe is mostly describing practices for the research and development activities. But once the development is completed and it's time to make a release, you usually want to give it to your customers. And in most companies there are functions that operate more closely in the customer front: sales and customer service. In smaller organizations these activities could be handled by product teams, but I assume that in a company that is big enough to benefit from the Scaled Agile Framework, these functions are separate.
Actually, linking the development with sales activities is a non-trivial task. I would maybe first broaden the scope of the Product Management with practices from other frameworks, for example Pragmatic Marketing Framework. For me the sales activities are essentially trying to identify customer's needs, understand their problems and look for solutions to those in co-operation with them. If the current offering can fit the customer's process as it is, that's great. But as good solution could be adding the customer needs to Backlogs and fulfilling them in the future. And developing them together would make sure they fit their needs.
Another addition that I would like to see in SAFe is the role UX and design. In the article about Sprint Execution, there's the DBT (define, build, test) loop. I don't think that's enough anymore. I would like to bring this more towards the direction shown by Lean Startup, Lean UX and Design Thinking. Testing should happen with real customers to validate the hypothesis made before the development. Otherwise the road to hell can be paved with good intentions. You might assume that customers want something, but without testing your idea in practice you could be on a totally different page. (Actually I first missed this SAFe UX article. But I think it should be brought more to the Team level also.)
So those are the couple of additions that I would be glad to see in the future. Without Sales there's no money coming in. And without good UX there's probably no sales.