What is the effect of the elimination of immunity conferred by prior law from liability in the context of personal injury claims?

"In this connection it is important to note that the elimination of the immunity conferred by prior law should not pose an unreasonable burden on the use of the property since all that is now required is the exercise of reasonable care under the circumstances (Basso v. Miller, 40 N.Y.2d 233, 241, 386 N.Y.S.2d 564, 352 N.E.2d 868, supra ). The defendant can always show that it would have been unduly burdensome to have done more (See 2 Harper and James, Torts, p. 1437)."