Several banks are likely TBTF right now, and they should be broken up along Glass-Steagall lines with retail/commercial banking split from investment banking. Ordinary deposits should be used to make loans according to years of safe practice, separate from risky and innovative adventures in investment banking.
The government should not bail out companies. No matter the size of the company, the government should let the company fail. They can split the company into smaller pieces during the liquidation process to evolve into smaller and potentially more successful companies. However, I don't think the government should have the power to restrict the size of the company. It should be a natural evolution in the economic model.