According to Nintendo's consolidated balance sheet from their recent shareholders meeting, Nintendo still has a hefty amount of money at their disposal.
Nintendo claims to have 474,297 million in “cash and deposits", which is about $4.7 billion in U.S. dollars; the Big N also has ¥320,918 million in short-term investment securities (which is about $3.2 billion USD). In total, Nintendo has ¥1,024,136 million (over $10 billion USD) in current assets; that number leaps to about $13 billion USD when you add in noncurrent assets such as machinery.
So, while the Wii U is not selling as well as anyone could have hoped, Nintendo is in no danger of going bankrupt any time soon; let's just hope it stays that way.
Source: Nintendo (Jump to page 12 for the financial report)