My understanding is that of the $245 billion loaned out, $175 billion has already been paid back - predominantly that given to the banks. What’s outstanding is really the stock of AIG and GM. If sold at market rate today, we’d lock in about $45 billion in total losses.
So, at worst, it’s around a $45 billion hit - not the $300 billion as shown in the graph.
There are rolling estimates and authoritative (?) statements from the CBO from time to time. The latest I could find from the CBO was 3/2011, http://www.cbo.gov/ftpdocs/121xx/doc12118/03-29-TARP.pdf . They say $11B is written off, $156B has not been paid back and $22B is “Anticipated Disbursements” (more TARP). Will the $156B be paid back? We’ll see. We haven’t fixed many of the problems around in March of ‘09 and I think the assumptions the CBO makes are optimistic at best.