Mercenaries the future of warfare?

[FM WarB]

An experienced US soldier retires to get a Contractor security job at thrice the pay, which taxpayers pay for.
US troops are fed and supplied by contractors, too. Are they not mercenaries, even if lowly paid? (except for the CEOs)
These contractors may or not accomplish their mission, but they still get paid, with no accountability.
In this sense, the rise of mercenaries to fight for and support the US army is a bad thing.