Things are not getting better in Detroit, they're getting worse. And as long as the series and teams depend on the Big 3 (and Toyota) for a significant portion of their sponsorships, NASCAR may have to bend some to keep the money flow near current levels. The current arrangement is good for NASCAR. But the Big 3 seem to be expressing the belief that it's not so great for them.
While Honda may eventually come in, I don't see premium brands like Mercedes, BMW, Audi or Volvo coming in - especially with the current engine package. No disrespect intended, but NASCAR's core demographic isn't one that those makers tend to focus on.