If those numbers are correct the GOP will need to start making real efforts with minorities within the next 5 years. Those numbers aren't sustainable long term.
Even if we just assumed that all constituencies remained static and old whites are being replaced by less conservative whites... that would be enough to cause the GOP problems... then you factor in the notion that the minority population is growing and it becomes implausible to continue this.
As others have stated, young whites are almost exclusively neo-Nazi/alt-right. The country will be voting like Mississippi and Alabama in 50 years.