As far as Bitcoin's code is concerned, there are no decimals. Sats are the base unit on the blockchain.

The concept that 100,000,000 sats = 1 Bitcoin is a social agreement external to the actual way Bitcoin works.

That said, it is such a longstanding social agreement that it would absolutely cause a lot of confusion and controversy to try and change it now.

Keep the 1 Bitcoin = 100,000,000 sats for the sake of consistency. To change it at this point would make a whole lot of folks scream "I thought Bitcoin didn't have inflation!" because no one actually knows how division works...