Personally I think so. Type certifications should expire after some reasonable time, and require a full re-certification under current rules and with current design review practices. I think this would also have other benefits, by discouraging improvements to e.g. fuel economy or pilot procedures slightly less, since the cost of re-certification is inevitable rather than something that can be avoided.

Grandfathering aircraft that exist indefinitely makes sense to me, but I don't see why designs should be grandfathered indefinitely for new builds, when we have learned a lot and increased our expectations significantly in the intervening years.