Half of the American workforce no longer needed?!

Pure free market; no crying towel needed: the bottom 50% of America’s workforce now takes 12% of overall income. It is hard to believe that the products and services produced by this half of America's workforce (70 million people!) would no longer be in demand over a few percent shift in overall income from the top 50% brought about by a $15/hr minimum wage (today's median wage).

Half the workforce, 70 million employees would receive an average $8,000/yr = $560 billion added to the cost of $15.8 trillion economic output = only 3.6% direct inflation.  Probably wouldn't lead to much additional inflation.  Economies with high minimum wages have median wages not much higher.  LBJ's 1968 median was only 25% higher than his approaching $11/hr minimum wage (at half today's per capita output!).
 * * * * * * 

My minimum wage worksheet -- my easily-could-have-been minimum wage double-indexed for inflation and per capita income growth:

yr  per capita    real     nominal  dbl-index   %-of

68    15,473    10.74      (1.60)                    100%
69-70-71-72-73              [real, low point -- 8.41]
74    18,284      9.47      (2.00)     12.61          
75    18,313      9.11      (2.10)     12.61
76    18,945      9.44      (2.30)     13.04        72%
77                                                               [8.86]
78     20,422     9.49      (2.65)      14.11
79     20,696     9.33      (2.90)      14.32
80     20,236     8.78      (3.10)      14.00     
81     20,112     8.61      (3.35)      13.89        62%
82-83-84-85-86-87-88-89                          [6.31]
90     24,000     6.79      (3.80)      16.56  
91     23,540     7.29      (4.25)      16.24        44%
92-93-94-95                                                [6.51]
96     25,887     7.07      (4.75)      17.85
97     26,884     7.49      (5.15)      19.02        39%
98-99-00-01-02-03-04-05-06                      [5.97]
07     29,075     6.59      (5.85)       20.09
08     28,166     7.10      (6.55)       19.45
09     27,819     7.89      (7.25)       19.42        40%
10-11-12                                                      [7.37]  
13    29,209?    7.25      (7.25)      20.20?     36%?