According to a report by Peter Williams[1], the US real estate industry has decided to adopt OpenID Connect for Web API authentication. I didn't know this, but the real estate industry is the largest sector in the US based on GDP. According to statistics based on 2014 by the US Department of Commerce's Bureau of Economic Analysis[2], it accounts for 13% of GDP. The second largest sector is the government sector, at 12.9%.

(Source) Author based on figures from the Bureau of Economic Analysis, U.S. Department of Commerce
According to Williams' report, after a "five-year" investigation [3], the real estate standards group decided to phase out OAuth custom profiles and standardize on OpenID Connect. The decision was apparently made because support from Microsoft and Amazon made it so easy to implement.
Cal Heldenbrand says:
Kudos to everyone. This is a big win for standards in general, and easy-to-use, interoperable standards in particular. I can't stress enough how much more enjoyable it has been working with OpenID Connect than it has been with SAML. [3]
Well, maybe I'm praising her a bit too much though (lol)
[1] Peter Williams, “Realty adoption”, http://lists.openid.net/pipermail/openid-general/2015-June/020812.html
[2] U.S. Department of Commerce, Bureau of Economic Analysis, “Gross-Domestic-Product-(GDP)-by-Industry Data”http://www.bea.gov/industry/gdpbyind_data.htm, “GDP by Industry / VA, GO, II 1997-2014: 71 Industries (XLSX) ”
[3] According to Cal Heldenbrand, "No, it was XNUMX minutes."http://lists.openid.net/pipermail/openid-general/2015-June/020813.html