No, coinbase is not the next mtgox.  Not even close. 

This past week, all exchanges have been overloaded, and coinbase handled it pretty well. 

I sold some bitcoins on coinbase on 11/18 and the dollars showed up in my bank account on 11/22.  It took 4 days instead of the normal 2 days.  Not bad for one of the biggest trading weeks in bitcoin history.

Mtgox hasn't had reliable withdrawals for months.  If coinbase starts doing that then you can call it the next mtgox, but it's not even close to that.