Even if you don't encrypt your communications, can you be sure that NSA will not store your data indefinitely? Sure, they can pass the raw unencrypted data through their system, parse out the important bits, save them in a database with a unique key for you and then throw away the raw data. Are you OK with that? They have lied in the past and might even keep that raw data as well. How will you know?
IMO, best bet is to keep it all encrypted. It sounds like an attempt to scare people into leaving their stuff open.
Exactly. We're operating on the assumption that they are telling the truth. I think that's a pretty stupid assumption.
This is just a scare tactic to get people to not use encryption, but it's also dimwitted because they could get a lot more mileage by saying "we can break all forms of encryption" and the American public would probably believe it (even with Snowden/a vocal minority calling out the NSA on the lie). The media would most likely propagate the lie because they don't seem to care about the rights/freedom of the people in the US more than creating a scare frenzy.
In summation, the NSA are liars and will keep your data regardless, so encrypt everything, don't put anything sensitive on Google, Skype, Dropbox (you'd have to be really stupid to do this anyway), and call your senator.
It's possible they're pushing the story now as a scare tactic, but the source of this information is a document from the DoJ authorizing the NSA to collect and store U.S. data in certain cases, leaked by Snowden.
IMO, best bet is to keep it all encrypted. It sounds like an attempt to scare people into leaving their stuff open.