The actual effect on fault tolerance and decentralization has to be put into context that currently over 50% of Bitcoin's hashpower comes from only 4 pools.  As BlockReduce scales the node requirements to have a node which does partial state validation would be much less then a if Bitcoin scaled in its current state.  That would mean that although there may be fewer people validating full state, there will be more people, and fewer pools validating partial state. I would argue that having partially validating mining nodes is advantageous over having a deminimis number of pools.  Having smaller economic entities decide on the fate of the protocol rather than a few large pools would be positive for the ecosystem.