That has to be the biggest pile of horseshit the Establishment has shoveled out about its invasions of everybody’s privacy in recent years.
And yes, I mean everybody. Everybody is a non-citizen of most of the world’s nations. So let’s suppose the NSA follows the law to the letter and never ever spies on US citizens without warrant. (A very generous assumption, in light of the well-documented principle that a lack of transparency always breeds corruption in organizations.) B.F.D.; just have CSIS, MI6, or ASIS* do that by secret agreement.
With the exception of a few dual citizens (easily handled by other agreements or by simply ignoring the law a bit), Americans don’t have British (or Canadian, or Australian) citizenship, meaning those foreign agencies can legally spy on Americans to their heart’s content, with access to US training and technology, and pass on only the “goodies” to the US after some pretext is used as “probable cause” for a US warrant.
So, so long as the Establishment has the ability to spy on everyone, they will (and already do) spy on everyone. Message content, not just contact records. Without any laws about warrants to get in the way. Your citizenship does not matter one iota. Sorry.
* And it’s almost certainly those three that are doing most of the spying-by-proxy on Americans, because those nations are both English-speaking and close allies.