De Silva still has two years on his contract but was only lured to Gosford by the prospect of working under his former youth international coach Paul Okon.
With Mike Mulvey now installed at the helm of last season's wooden spooners, the 21-year-old attacking mid is expected to cut ties.
A move by Melbourne City for the youngster fell through but it is understood his agent, former Socceroo Vince Grella, is canvassing other options in the A-League and abroad.
Mulvey brushed of questions about De Silva: "Danny wasn’t here today, he’s been given a couple of extra days off… no problem."
Brisbane Roar's former title-winning coach said he was happy with the pace of recruitment but hinted at more experienced players joining the line-up.
"We’ve got a couple of players in the pipeline that we’re talking to at the moment and we’ll be able to give you some exciting news in the coming days I think," he said.
"We’re looking at a few other leaders to bring into the club." 
Recovering duo Antony Golec and Tom Hiariej returned for the start of pre-season but Jonathan Aspro was described as "a long way off".
Mulvey was was watching on when the Mariners were thrashed 8-2 at home by derby rivals, Newcastle Jets, and has made no secret of the fact he wants to erase the humiliation of 2017/18. 
"The mental challenge is very, very important" he said.
"When I first came in and I saw the debacle of the last game of the season and I watched from the stands – you know something needed to change.
"We’ve made a bit of a seachange – the problem is the players have got to respond to that. Every player has got the opportunity to get themselves a shirt in the squad… every man for himself, really.
"This is going to be a team that is competitive right to the very, very end. And it starts now."