Ten Doeschate was Netherlands' second top-scorer at the men's T20 World Cup qualifiers in the UAE, making 233 runs in nine innings at a strike rate of 136.25.
Seelaar knew the importance of having a performer like that at an ICC event but insisted the decision would be "entirely Ryan's alone".
"There are no concerns, Ryan is one of the fittest blokes around in the change room," Seelaar said after their win over Papua New Guinea in the final. "I'm not sure what his decision is going to be, it's entirely up to him. He's got a contract extension at Essex, which will keep him busy, but he's told me he'd like to play another World Cup. We have to see when we get there, but it will be helpful to have his experience and quality, which we don't get very often.
"He's the sort of guy who can win you games at No. 5 from any sort of position. For me, he'll be quality to have in Australia. Having a guy like him helps not just on the field, but off it as well. There's a lot of knowledge you can turn to, take a lot of information from when he's out on the field. Having him out in a tough chase eases the nerves down a little because he's such a quality player. He's done it in tournaments around the world, so his quality and experience are invaluable not just for me but the whole team."
Seelaar also heaped praise on Roelof van der Merwe, another allrounder who delivered at crucial moments, most notably in the final with figures of 2 for 15 in four overs. "The fast bowlers as a whole have been good, but I have to single out Roelof van der Merwe," Seelaar said. "Be it with the bat, ball or on the field, he always does something special."
Looking ahead to the next 12 months, the captain hoped Netherlands would be able to build a pool of 20-25 players, as compared to the 15 to 20 they have currently. He also hoped clarity of roles and clear communication would be the endeavour as they looked to sustain this momentum going into the T20 World Cup.
"You can't go in depending on 15-16, we need a pool of 20-25 guys to choose from when we go to Australia," he said. "We've got a couple of players waiting in the wings, but this team has set high standards. It's up to them to live up to the standards. We've to keep working on our fitness. Tournaments like these break you down physically and mentally. We've got Pakistan up next at home, which is going to be tough. Generally, we should build a squad of 20-25 who all have an equal shot at going to Australia.
"We want the guys coming in to play a certain way. We want to pick guys suitable to roles, but it's not just about winning games, it's about coming from hard practice and having good solid plans so that everyone's clear and have the freedom to do something special. We've to create a hard-working culture to make sure we maintain this success and bring it along by the time we get to Australia."