With the possible collapse of the Congressional health care effort, health insurers might seem to have reason to celebrate. The legislation threatened to remake much of their business, with the prospect of burdensome government regulation and less profit from selling coverage to individuals and small businesses.

Indeed, some insurance stocks initially rose on expectations that the Massachusetts Senate vote might have derailed the Democrats’ health overhaul. But more of the same might not actually be such good news for insurers, some health policy experts and Wall Street analysts say.

“In the longer term, reform would have been better for them,” said Les Funtleyder, the health care strategist for Miller Tabak & Company, a New York investment firm. He acknowledged that insurance stocks might benefit in the short run as investors expressed their relief over the diminishing odds of a health care bill.

The health care legislation under construction in Congress would force the insurers to conduct business very differently, but the companies had already agreed to some of the most fundamental changes. One was their pledge to offer coverage to everyone, regardless of medical status, if the government could ensure that people, even the young and healthy, would have to sign up.