Future Spanish-speaking population in the United States

A quote from an article here says that:

A recent study titled: "The Future Use of the Spanish Language in the USA" estimates that the number of Spanish-dominant and bilingual Latinos will increase by 45 percent over the next two decades therefore adding 12.4 million Spanish-speakers to today's population.

That would bring it to about 47 million or so by then. The most recent census shows the Spanish-speaking population to be 34.5 million.