Paul was still a man of the Curia, which explains Humanae Vitae.  The Curia did not make him do anything he did not want to do and he brought some of them into the modern world, until John Paul did all he could to bring it back to a more traditional bent - with Benedict continuing - especially with the translations of the liturgy.  Could the Church have accepted a more liberal successor to Paul?  Probably not.  If it had, we would have liturgical gay marriage by now and would not have returned to the more literal translation of the Roman Rite.  Still, he moved to ball forward enough so that Francis could pick it up again - although I don't expect that much change here either.