A friend of mine went to Farnborough this year, and he visited the Sukhoi stand there.
Since his favourite aircraft is the Su-37, he asked about the project.
Sukhoi built not one, but two aircraft, the 711 and 712.
The 711 crashed on December 19, 2002 due to an FBW failure, but the 712 still exists.
They wouldn't say if it is still flying, but they told him that the data from the Su-37 project is used to develop further TVC aircraft, like the Su-30MKI.
By the way, the Su-37 is not 'just' an Su-35 fitted with AL-37FP engines, it also has a completely redesigned glass cockpit, with sidestick and a single throttle to control both engines.