Like said, you might introduce a single point of failure. How about for instance the censorship resistance? What would the future look like in terms of number of block producers when groups bundle? Is there a minimum number of block producers and is concentration limited in numbers? Or are these the questions that we need to answer the coming months?
There is concern about whales owning more than one block producer, and the fact a group of 66.7% of block producers could get a consensus for nullifying the account of a whale. Also, the arbitration process is unclear, who wants to be the arbitrator of a big-whale, as this could have big consequences for the arbitrator. Pareto principles work against the stake model, especially when all the little fish are not aware and not unite. These are very interesting conversations to have, and the governance channel of the EOS go channel is very busy at the moment. As the constitution and details on governance and arbitration touch all vested members ...