Kane Williamson will opt out of a handful of internationals in January to take up a contract in South Africa's Twenty20 league but plans to keep playing for New Zealand for as long as he can, the batsman said on Thursday.

Williamson announced on Wednesday he had given up the captaincy of New Zealand's white-ball teams and would decline a national contract for the 2024/25 season following the team's early elimination from the T20 World Cup.

Arriving home on Thursday, the nation's best batter said he wanted to manage his schedule more carefully.

"I want to play as long as I can. I love playing for New Zealand, I've really enjoyed my time captaining," the 33-year-old told reporters at Auckland airport.

"But I'm excited with what's next for the team in terms of their leadership as well and I'm looking forward to being a part of that.

"In terms of a time-frame (for my career), it's difficult to say. I want to keep being fit, keep doing as well as I can, keep trying to improve and play as long as I can."

New Zealand crashed out of the opening phase at the T20 World Cup co-hosted by the United States and the West Indies, having made the semi-finals of the previous three editions and the final in 2021.

Long-serving fast bowler Trent Boult confirmed he will not be part of the New Zealand setup for the next tournament in Sri Lanka and India in 2026, while fellow quick Lockie Ferguson has also opted out of a New Zealand contract.

With a number of senior players over 30, New Zealand may face a difficult rebuilding phase and struggle to be competitive by the time the next World Cup rolls around.

Williamson, however, said the squad was in a good place.

"We know that there are more events that we need to keep building towards and largely the team is in a really healthy place," he said.

"There are some really talented younger guys coming through and (still) a number of experienced players as well."

Williamson is the latest elite player opting for T20 franchise cricket over international duties in an increasingly crowded calendar.

He said it was up to the world's cricket boards to monitor the situation and that every player had different priorities.

Speaking of his own playing future, he said it was "one year at a time".

"(It's about) managing that time as your career develops ... Family's a big part of that. Doing that as well as you can is really important."

(Reporting by Ian Ransom in Melbourne; Editing by Peter Rutherford)