they just need to add the guide background or another wilderness type background to the basic rules and you have your ranger by using that with fighter or rogue.
http://dnd.wizards.com/articles/features/handful-class-ic-histories
Discussing the history of the "key classes"...
That's intersting given our discussion here of using a fighter in the basic game to stand in for ranger. That's what they did in the starter set - making pregens that could made from the basic rules alone. Of note, the miniatures released to coincide with the debut of 5e correspond to the starter set pregens with an archer fighter. And the characters in the web comic are based on those miniatures. And the article linked above references the web comic implying that the arched character is a ranger, not a fighter.
There is no doubt in my mind that this is exactly how they are thinking about it.But after thinking about it, I can see a reason why they might emphasize the Ranger as they've been doing, and yet still not include the Ranger in Basic. If the Basic Rules are seen (from their perspective) as the main 'hook', then it makes sense to plug the Ranger as a key class, Basic is the hook, the Ranger being the pull (not THE pull, but A pull). While I think we (or, I) want Basic to be the essential D&D, I think they might view it more as it is enough to capture essential D&D (because: Archer Fighter + Custom Background are Basic). If they say that the Ranger is a key class, a classic class and then not include it in the Basic Rules, then it must be a hook, a 'come hither'.
If they are going to add any class to the basic 4 it should be the bard. 4 basic roles are covered plus a class that can kind of do all 4.
That was an interesting read. Thanks.
Someone asked about it on twitter, Mearls response:
"thought about it. it is the most popular class beyond the core four, but we ultimately decided to keep Basic as lean as possible"