Where 10% income shift from 1% to 99% could come from

To restore equitable US income share, 10% of overall income needs to be snatched away from top 1% earners and restored to the lower 99% (1% takes 20% today): $13 trillion over a decade.

Jeff Stein's Washington Post column suggests a road to half way there:
"1. $720 billion/decade: Ocasio-Cortez’s suggestion for nearly doubling taxes on people earning more than $10 million;"
"2. $3 trillion/decade: A wealth tax on the top 1 percent similar to those in Europe;"
"3. $3 trillion/decade: Doubling income taxes on the top 1 percent."  (multiple angles)
http://www.washingtonpost.com/business/2019/01/05/ocasio-cortez-wants-higher-taxes-very-rich-americans-heres-how-much-money-could-that-raise/

The other half of the lost 10% could be repatriateable via repairing atrophied labor union density (6.5% in private employment and dropping!) -- empowering employees to once again divvy up a decent share of the profit pie with ownership.  Illegal (in case we've forgotten) union busting has become so deeply embedded in our (not European) labor market DNA that we seem compelled to skip -- to forget about -- old fashioned organizing.  The road left: side-step to Congressionally mandated, regularly scheduled union certification elections?
https://onlabor.org/why-not-hold-union-representation-elections-on-a-regular-schedule

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[late note]  Constitutional question about fed tax on wealth?  Apparently we can get pretty much the same 2% of wealth revenue from roughly the same people with an income tax surcharge of 20% on income above $50 million.  Income tends to be pretty regularly 10% of wealth for this group.  (graph provided)
https://www.motherjones.com/kevin-drum/2019/01/heres-how-to-enact-a-wealth-tax-that-the-supreme-court-wont-kill/