It could be. There's a very small window of people with insufficient retirement savings--below a 50% replacement ratio benchmark. Not everybody who has no pension plan has inadequate retirement income. It's a relatively small group and tends to be in the lower-middle to middle class. It would be less disruptive and perhaps just as successful to target that group--which might be those making between $47,000 and $60,000, for example--if we can solve that problem.
I don't know how disruptive it would be to the availability of other pension coverage. If you start doubling the taxes right away, I think you'd see more employers killing the pension plans they still have and getting out of the liability, the extra administration, and the cost.