Anything that triggers a big tax on Berkshire shares is probably a lousy idea.

I've moved almost everything I can without triggering taxes into Berkshire/cash from indexes over the past few months. Everything "trapped" in indexes would trigger at least a 20-30% immediate value loss. I think I'd rather hold those positions (and run the risk of being worse off if the market drops 40%+ in the near-term than pay a huge tax bill).

If it were my pile, I would either sit on my hands or do the planned sales with the intent to purchase something else offering general equity exposure. I think you'll find that alternatives are either Berkshire-like (e.g., long-term value funds) or offer index pricing risk given today's prices (e.g., S&P @ 30x PE). When I go through this dilemma daily, I end up consistently sitting on my hands and lamenting my trapped VOO shares.

Anyway, so in summary, do nothing or sell a little, but 10 years of dry powder already feels excessive so you're probably best off doing nothing.