Not forcing people to pay for things they neither need or want, like abortion, maternity, pediatrics, drug rehab, etc. Will make it much more affordable. Allowing young healthy people to buy catastrophic insurance would be an incentive also rather than a mandate. High risk people could be put into another pool and if their coverage needed assistance it would be a lot less expensive for everyone to just do that than the way the ACA socialized plan is.
I'm not being a hypocrite here. I have Medicare Part A but opted out of everything else.