Pompey's traumatic campaign, during which they have used more than 50 players and almost went bust before the PST completed their takeover earlier this month, ended with a 3-2 defeat at Shrewsbury.
Whittingham has already said he wants to keep the bulk of his current squad in a bid to bounce straight back from relegation to League Two.
"There's a lot going on in people's heads at the moment with talk about who's staying and who's going," he said.
"A lot of people have been watching our players closely, but we'll try to keep as many of them as we can.
"It's been an unbelievable season. I don't think any club has experienced anything like it in the past and I hope no-one does in the future.
"Football is a rollercoaster ride and there are always ups and downs. There was a big peak last Saturday, although we've now come down a bit."