The Omaha resident, famous for both his billions and his frugality, built Berkshire Hathaway into a financial empire.
The chief executive once said that if the pair were in a sinking boat together and shareholders could only save one of them, they should pick Jain.
He told CNBC that their promotion is "part of the movement toward succession" at the company.
The legendary investor's departure would put the company into unchartered territory for retail investors.
Vancouver-based Odlum Brown analyst Benjamin Sinclair thinks it's a bit premature to speculate on who, between Abel and Jain, is the frontrunner for Buffett's job once the 87-year-old billionaire departs the company.
Berkshire stock rose Wednesday even as the broader stock market logged a modest decline as Buffett laid out a road map for his eventual likely successor.
"I love what I do at Berkshire", he said. "I can't wait to go to the office in the morning". "There's nothing I'd rather be doing". This takes the size of Berkshire's board of directors up to 14 from 12. "Now, when it happens or how, or anything else, I don't know".More news: Hina Khan breaks down because of Luv Tyagi's harsh comments
The cryptocurrency halo has been good for other companies too.
Bitcoin bought by Thiel's firm are now believed to be worth hundreds of millions after the currency's surge a year ago.
Still, Buffett was conflicted about the change in corporate tax rate, arguing that American businesses don't need any cut, he said. "Once Warren and Charlie are gone, there will be intense pressure to start paying a dividend", he said.
In the CNBC interview, Buffett repeated that Berkshire's board, whose members include Microsoft Corp (MSFT.O) co-founder Bill Gates, can install a new chief executive within a day when he steps down, dies or becomes incapacitated. "The key players are still there".
"Net we're buying", he said.
While they may be selling some stocks, Buffett said Berkshire Hathaway is a net buyer of stocks.
CEO Warren Buffett believes the euphoria over Bitcoin won't end well for investors - but he's not about to short Bitcoin futures either.