Unless your proposal is that people who never worked should be left to die in the gutter (and I'm sure it isn't) if they need residential care but aren't able to pay for it privately (and most of them won't be able to) they are going to have to get it at public expense. So, one way or another, means-tested support for residential care looks inevitable.
So the consequence of providing a second, social insurance-based scheme for funding residential care is that people who, currently, don't get support (because they don't satisfy the means test) will get it. That will have to be paid for, either through higher taxes or higher social insurance contributions (or a bit of both). If we assume that the German contributions are set at a level high enough to actually finance the residential care (which is not necessarily the case)and that a similar level of contribution would finance residential care in Ireland you're looking at an extra 3-3.5% on social insurance contributions or tax rates (or maybe a bit less, because we don't have a ceiling for assessable earnings).
Most people would pay, directly or indirectly, this extra contribtuion all their working lives and get no benefit ffrom it (because only a minority of people ever move into residential care). They'd be doing this so that other people, who don't satisfy a means test and therefore could afford to pay for themselves, wouldn't have to. They might not think that that was a great deal.
I could see this being controversial, to be honest.