There was a sizable crowd inside Greektown Casino-Hotel on a recent Wednesday afternoon with groups of predominately middle-aged and older gamblers — several with walkers or canes — seated before rows of flashing slot machines, some dragging on cigarettes.

These weekday regulars are a dependable and crucial crowd for all three Detroit casinos, especially for Greektown, the No. 3 property by size and revenue, which owner Dan Gilbert intends to sell for $1 billion next year in a deal involving Penn National Gaming.

After overcoming its 2008-2010 bankruptcy and then more lingering profitability problems, Greektown Casino is said to be finally out of the red and in the black. And a recent analysis by Moody's Investors Service anticipates that Greektown and local rivals MGM Grand Detroit and MotorCity Casino Hotel have bright horizons ahead with steady and stable revenues.

The prospect of legalized betting on professional sports in Michigan could be an additional revenue stream for Detroit's casinos if future regulations require that sports bets happen at the casinos or through one of their Internet portals.

The lame-duck state Legislature last week approved a bill that opens the door to sports betting. The same bill authorized online gambling on things like poker through websites for the three Detroit casinos and 23 tribal casinos across Michigan.

“I do think the three Detroit casinos could be looking at a material upside as a result of the legalization of sports betting," said Alex Calderone, managing director of Birmingham-based Calderone Advisory Group and a casino gaming expert. “A lot of it is going to depend on how the state regulates the industry, and how many times are they going to slice that pie” of betting revenues.

The health of all three casinos that employ thousands of unionized workers is crucial for the financial health of the City of Detroit as it aims to avoid a repeat of its own municipal bankruptcy.

Wagering taxes are the city's third-biggest income stream, after incomes taxes and state revenue-sharing payments, and comprise 17 percent of its annual revenues, according to city documents.

A Free Press analysis shows that all three Detroit casinos are doing more gambling business now than a decade ago, even as Ohio opened its own casinos during that period and the early novelty of local gambling may have worn off for some people.

Combined gambling revenues at the three casinos totaled $1.43 billion in the past 12 months, or 5 percent more than the same period from December 2007 through November 2008, according to the analysis of Michigan Gaming Control Board data.

Those figures do not include the casinos' non-gambling revenues such as food, drinks, hotel stays and events.

"I don’t see a lot of growth on the horizon, but I think what you will see is a steady, stable, mature income stream from all these three properties," Calderone said.

One wild card is the outcome of a long-running effort by the Sault Ste. Marie Tribe of Chippewa Indians to open a small casino in Huron Township near Metro Airport. Such a casino could draw some business away from Detroit.

The tribe is currently challenging a 2017 decision by the U.S. Department of Interior that denied the tribe's request to have land for the casino put into trust, a necessary step for opening any casino so far away from the Sault's tribal lands. The department also denied the tribe's application for Lansing casino land.

Jacob Miklojcik, a Lansing-based gaming consultant, said the significant number of weekday visitors at Detroit's casinos has long been considered one of the market's strengths.

“The one thing that Detroit has always had is the people who are using the casinos 24/7," Miklojcik said. "I have always been amazed. Even in Las Vegas, you go to those casinos in the early afternoon — there’s no one there. In Detroit, we’ve always had that base midday. That has always been very impressive to me."

The long-term health of Detroit's casinos is likely tied to the strength of the region's economy, particularly the confidence and discretionary income of all those casino regulars.

Future gas prices also will matter. All three properties experienced big jumps in gambling revenues after gas prices plummeted in late 2014.

"When people have money in their wallets, they have money to go to the casinos," Calderone said.

Contact JC Reindl: 313-222-6631 or jcreindl@freepress.com. Follow him on Twitter @JCReindl.