Hirst could link up with former Sheffield Wednesday striker Chris O'Grady at Chesterfield.
Dennis is said to have interested Burton Albion earlier in the summer and counts several League One sides among his admirers.
Kristian Dennis of Chesterfield [second right]
As such, it is claimed that Chesterfield boss Gary Caldwell is making contingency plans, of which Hirst is a part.
The 18-year-old is extremely highly regarded at Hillsborough - and beyond - having scored 40 goals for Wednesday and England's youth sides last season, with his form prompting a failed bid from Everton in January.
But securing first team football could be high on both Hirst and the Owls' agenda this coming campaign, and temporary spell down the road at Chesterfield could have its benefits.
The son of legendary Wednesday striker, David, Hirst Jr has appeared twice for Carlos Carvalhal's first team, but not since the mid-season arrivals of Sam Winnall and Jordan Rhodes.
Jordan Rhodes of Sheffield Wednesday
Should he become a Spireites player this summer, Hirst could end up partnering former Owls striker Chris O'Grady.
Should Sheffield Wednesday send Hirst to Chesterfield?