I think the issue with tweaking the state pension/retirement age is the uncertainty it helps generates, I would prefer the government to say something like "OK anyone under 45 today it's 70" and be done with it. I picked 45 because that still leaves someone of that age today 25 "working" years to sort out their pension.
I have a bit of a problem with the "retire at 70" proposal. I do "indoor work with no heavy lifting" and am likely to be in good physical health until the age of 70. My value to clients is largely knowledge-based so as long as I stay current and don't get early onset dementia then it's likely that I will be able to work until I'm 70.
On the other hand, I'm not aware of a huge demand for physically frail unskilled employees so it's going to get even worse for the "have nots". Someone on minimum wage is also unlikely to make extra provision for their retirement, all their income goes into putting food on the table.