If the DoJ wants access to US citizen data...
... it has to force them (and the company managing them) to store those data on US soil only - if that's constitutional.
I can't really see how the DoJ can have access to data managed by US companies (or their foreign branches) and stored elsewhere, without colliding with many jurisdictions abroad.
Anyway, this way the DoJ is nailing the coffin of any treaty between US and and foreign countries regarding non US data stored by a US company.
Good my cloud provider (not a US one) lets me choose where my servers are run from.