Maybe the OP thought this was announcing Buffett's successor or that Buffett himself was stepping down?
I guess the one big thing is that Todd Combs is out at Geico which is pretty bad news for the firm as he was tremendous at running Geico and helping Buffett and Munger in an investment capacity.
Who ever gets the new CIO role at Berkshire is going to have a field day. They currently hold about $382B in cash.
You can invest in alot with a 1/3 of Trillion dollars and you can outright buy the vast majority of companies with a bank roll that big.
My theory is that Buffett is hoping for one last large crash before he retires so he can go shopping for distressed companies.
With so many long term people announcing they will be leaving within the next 2 years this announcement sets the table nicely for a new CEO(probably Greg Abel) and new CIO to pick their team.