Basically, the accidents have opened a can of worms with the B737, the deeper they go the more they find wrong. Issues which have sat quietly under the radar because they hadn't yet caused problems are coming out into the open. The aircraft is going to be taken apart to the last rivet and evaluated against modern safety standards, 50 year old bicycle chain and cable technology won't cut it in the era of fly by wire.
Every aspect will be looked into from technical to the certification process and no one is going to put his head on the block by signing off unless numerous experts and committees give it the OK.
Universities will be using Boeing's response to the accidents as a case study in future years.