The Everton defender and striker have both been linked with exits from the club.
The highly-rated young duo have both been linked with exits from Goodison Park exit this summer after a disappointing campaign.
Lukaku in particular has been attracting interest from several top European sides according to rumours, while his agent seems determined to get a move.
Stones meanwhile, was targeted by Chelsea last summer, and a move to Manchester City to join Pep Guardiola has been mooted for him.
And Gray concedes that they are both the most likely to leave, but says the club might be able to convince them to stay if they make the right moves.
“I think if Lukaku wants to leave he’s gone, and if John Stones wants to leave he’ll go. I hope that Everton can keep more than they lose,” he told talkSPORT.
“I think those are the two that are more vulnerable, but if somebody can sit down and say ‘give us 12 months we’re going to aim for the stars’, they might be able to keep them.”
Both players would surely be wise to wait and see who the new manager at the club will be following Roberto Martinez’s departure.
The Catalan was sacked on Thursday evening after a disappointing campaign and there are currently a number managers being linked with the job.
Southampton manager Ronald Koeman has appeared as the early leading candidate and perhaps both could be tempted to wait and see before making their decisions.