Opinions differ on the causes of the financial crisis; some economists suggest it happened because of a combination of several causes. In the US sub-prime mortgages were involved, in that mortgages had been given to some who were poor repayment risks. When these were bundled into other securities, an unknown risk was being marketed, with some institutions heavily over-extended with potentially bad debts. It should be pointed out that it was US government policy to extend home ownership to low income people. The two agencies Freddie Mac and Fannie Mae were both encouraged to do this. The process of 'red-lining,' drawing lines around city zones inside which no mortgages would be given, was outlawed. It might also be noted that most of those who received mortgages, including low income people, continued to pay their mortgages payments and successfully became home owners. Only a tiny proportion were defaulters. It was the unquantifiable nature of the risk that caused problems.
Others have pointed out that the Federal Reserve Bank made a policy of cheap credit. They did this to weather crises and prevent economic downturns. The Bank of England did some of the same. When money was cheap, so was risk, and the message encouraged financial institutions to undertake riskier ventures. It was as if all the traffic lights were stuck on green, and everyone pressed ahead at speed.
The lesson is that governments and central banks were at fault, as were reckless traders taking huge risks to bring greater returns. It was not capitalism itself that brought about the crisis, but rather the inappropriate behaviour of some of the parties involved, including government. Neither was it regulation. With the possible exception of the pharmaceutical industry, the financial sector was among the most tightly regulated in the world. It was unsuitable regulation that sent the wrong messages and brought about wrong behaviour.
Capitalism has not been replaced and almost certainly will not be replaced, in that no-one has found a better way of generating wealth or of improving living standards over the long term. It experiences shocks and crises from time to time, and it is partly a learning process. After each crisis it is modified to prevent the same happening again. But there may well be new and different crises in the future, and new ways will have to be found to deal with them.