No possibility of reverter or right of entry or re-entry for breach of a condition subsequent is alienable or devisable; and no conveyance thereof made after the effective date of this Act shall operate in favor of the grantee, or persons claiming under him, by estoppel, inurement of title, or operation of Section 7 of an Act entitled “An Act Concerning Conveyances,” approved March 29, 1872, as amended.