The commitment comes after the Welsh LMCs conference this month unanimously supported a motion urging the GPC not to negotiate away MPIG 'until appropriate financial arrangements are put in place'.
Commenting on the continuing support for MPIG, GPC negotiator Dr Peter Holden said: 'If the government had its own way it would get rid of it within three to five years.'
When asked if he believes it would be stopped, Dr Holden said: 'I think over a period of 20 years it will be.'
Fellow GPC negotiator Dr Chaand Nagpaul said there was no official date being proposed by the GPC for the abolition of MPIG and he refused to reveal any 'unofficial' timescale.
'Our position has been that there is no sense in having an arbitrary timescale', he said. 'Removal of reliance on MPIG requires investment in the contract.'
GPC chairman Dr Laurence Buckman said 100 to 200 practices would be in 'very serious trouble' if MPIG ended. 'No-one is going to do a three-year disappearing trick,' he said. 'If we defunded these practices, some would close and no government is going to do that.'
BMA health economist Jon Ford said some practices' MPIG payments were too large to be eradicated on a 'rising tide basis'.
'There would have to be a pragmatic arrangement, something like the old PMS contract but the government wants to phase them out,' he said.
'It is feasible to end MPIG provided there is some increase in resources. A lot depends on how the economy is going.'
Mr Ford said he was reluctant to project how long it would take to buy out MPIG based on current levels of investment in the contract.
A DH spokeswoman said MPIG was an issue for the GPC and NHS Employers.