IMHO and this is serious, the biggest contribution in inFamous is to enrich/fix (boring) travelling in open world games. It is the only open world game where I have gone more than halfway through (still not completed though). Therefore, I hope they continue to spice up open world game mechanics.
RDR seems to have a great ecosystem. inFamous may want to look at its own games and see where it thinks open world games should go. I am all ears (at the moment).