Everton's Barkley and Arsenal's Gibbs have spent time with the Three Lions senior squad, while West Ham United star Morrison has impressed at Under-21 level.
"We've got a big nucleus of players who we've used, tried and tested in these recent squads," Hodgson told talkSPORT.
"We've got that nucleus already but we've got to keep a very close eye on the younger ones in the squad; the Barkleys, the Kieran Gibbs, who haven't spent as much time with us but look very interesting.
"Then of course you've got some exciting talent breaking through in the Under-21s."
Hodgson went on to praise Morrison for his performance in England Under-21s' 5-0 victory over Lithuania, in which the Hammers star found the net twice.
"He was very good and his goal shows all his qualities; his poise, his balance and not least of all his composure," he added. "That step over to beat the goalkeeper was a bit special I thought. I was delighted with his performance."
England booked their place in Brazil with a 2-0 win over Poland.