Xbox One Slim Rumored For E3 Debut Following Brazilian Regulator Leak
The rumor has to do with the wireless chip Microsoft uses in its Xbox One. Apparently it's testing a new version of the wireless chip for an unannounced Xbox One model, as several filings with the Federal Communications Commission show. Related details of the filing are currently hidden by the FCC under a non-disclosure agreement (NDA) until June 25, which effectively keeps things quiet until after E3. One reason to do that is if Microsoft was planning to announce new hardware at the convention.

A leaked photo and details leaked by Anatel, the Brazilian equivalent of the FCC, further support that scenario. Unfortunately for Microsoft, Anatel isn't as good as the FCC at keeping secrets or abiding by NDAs for photos, so now there's a photo of the unreleased wireless chip making the rounds.
If Microsoft does end up releasing a slim version of the Xbox One, it will be interesting to see if there are any notable upgrades inside. It was just over two weeks ago that Phil Spencer, head of Microsoft's Xbox division, downplayed the notion at Microsoft's 2016 Build conference.
A slim version with essentially the same guts wouldn't run counter to that statement, though if Sony does end up releasing and upgraded PS4 that can game at 4K, Microsoft may want to rethink its stance.