Shell will presumably continue to repurchase class-A shares as long as they trade at a discount to the class-B shares, which they undoubtedly will due to the 15% Dutch tax withholding on dividends from the class-A shares (but not the class-B shares).
Eventually, Shell hopes to consolidate the two classes of shares into one, but this will require the approval of the Dutch government.
“The efficient-market hypothesis may be the foremost piece of B.S. ever promulgated in any area of human knowledge!”