The Environmental Protection Agency issued a final rule Wednesday replacing former President Obama's signature Clean Power Plan (CPP) with a far more modest version controlling carbon dioxide emissions from America’s coal plants.The big picture: This fight, like many in Washington, is big on symbolism and lacking in substance. While it was supposed to help President Trump save the coal industry and gut the heart of his predecessor's climate agenda in one swoop, the reality tells another story.Reality check: America's coal industry continues to decline, driven by a host of factors separate from the Obama-era regulation, largely — but not only — because plentiful supplies of natural gas provide power companies a cheap, cleaner-burning alternative. Meanwhile, the CPP never actually went into effect, despite the hype from Obama administration officials and environmentalists. In an unusual move, the Supreme Court temporarily blocked the final rule in February 2016 to let litigation play out.Details: The rule aims to reduce power-plant CO2 emissions by as much as 35% below 2005 levels in 2030, according to the EPA, which said this decline is also due to "expected industry trends," highlighting the ongoing shift away from coal to natural gas and renewable energy — irrespective of both Obama's rule and Trump's efforts to repeal it.Between the lines: The EPA's assessment is an implicit acknowledgement that its new rule isn’t going to bring back coal.America's greenhouse gas emissions, like much of the rest of the world's, ebb and flow with economic growth and demand. After a marked decline due to the shift from coal to natural gas, which burns far less CO2 than coal, U.S. energy-related emissions are expected to decline again slightly in the coming years.The intrigue: Myron Ebell, a top director at the Competitive Enterprise Institute, a conservative think tank that disputes that climate change is a problem, said Wednesday that his group will likely sue EPA over the rule, arguing the law doesn’t allow such regulation on CO2. Ebell, who was an adviser to the Trump transition team, said this would be the first lawsuit his group would file against Trump’s EPA, which has been mostly pushing policies Ebell supports.What's next: Expect lawsuits from environmental groups and Democratic-led states. In other deregulatory news, EPA's other big controversial rollback — freezing Obama's auto efficiency standards — is expected soon.Go deeper: The U.S. coal industry is choking