If you think tougher gas emissions are the answer your nuts... You can bet your ass the gov is watching the webs.
I'm not advocating tougher gas emissions, just speculating that when it happens, there will be more pushback than what they currently see from diesel owners. It is just a numbers game. If the same percentage of gas particulate filters see issues as DPFs, there will be hundreds of times more people mad about it.
If it was up to me, I'd have one emissions standard for all fuel types in a given weight class. Cars would meet standard A, trucks would meet standard B. I don't care if they are gas, diesel, electric, propane, or nuclear. Make the playing field level. Then set the standard somewhere sane. I think we are at the point where cars aren't a major contributor to the emissions in the US. From what I read, a large amount actually comes in on the tradewinds from China. So what is the point of super strict vehicle emissions laws if it isn't going to change the atmospheric pollutant levels? Leave them be while we sort out the other issues, then revisit it in 10-20 years.
If the EPA really cared about the planet, they would be doing everything they could to help China clean up its act, but they aren't. The tighter they make the laws over here, the more manufacturing moves overseas where the factories can pollute more. But I think I am preaching to the choir here.