There were lots of problems with the pre-DMG AMA series, on the AMA side and with some of the manufacturers. But aside from sugar water makers, the only companies with any incentive to support motorcycle racing are the manufacturers and the aftermarket companies that cater to buyers of the manufacturers' products. Any business model that doesn't court their support is doomed. There are not enough motorcycle racing fans to entice the supposedly coveted outside-industry sponsors, so the NASCAR model won't work. It's not even working that well for NASCAR these days. The supposed road racing example--DMG's Grand Am--only survives because there are more rich guys willing to blow money on car racing then there are for motorcycle racing.
And all of the above doesn't take into account the cascade of idiocies that Roger Edmondson's reign inflicted on the series, knee-capping it just as the economy was imploding.
It's dead. It won't be revived until someone takes it from DMG and starts from scratch.