Biggest challenge that Erickson would have is the need to team with an OEM. I doubt they have the personnel needed to wade through the ten miles of bureaucratic bumpf that would be thrown at them to complete prior to getting funding for "a few S-64F". Need several Congressional delegations to support as well.
Perhaps sad, but it is the way of things in liberal western democracy these days.
I do note that they are proposing to use Sikorsky Matrix. That means Lockheed Martin. That is a potential means forward.
I disagree.
Consider this proposal from the perspective of VIKING in Canada. VIKING has been overhauling and re-building deHavilland of Canada floatplanes for longer than most people can remember. Few of Harbour Air's DHC airplanes have many original components remaining after being re-built a dozen or more times. They have Supplementary Type Certificates for a variety of modifications and Parts Manufacturing Authority for all the high-wear components. By the time they bought the Type Certificates from Bombardier/DHC, they could almost build a DHC airplane from scratch. When they bought the Type Certificate, VIKING inherited hundreds of form blocks, allowing them to build all DHC components on original tooling. From there it was a simple (paperwork exercise) to combine all those STCs, PMAs and TCs into new-production DHC-6-400 Twin Otters.
With Erickson's decades long experience in over-hauling and upgrading Sikorsky Sky Cranes, it is more a paperwork exercise to start new production. I think they are already building new Skycranes for civilian contracts.