I bought 4,000 ETH back during the presale in 2014, with an idea to take a nap and come back in 10 yrs to see how it was doing. I have never touched the coins, never even opened a wallet.
Do I now own 4,000 ETC? or 4,000 ETH? or 4,000 of both ??
You own 4,000 ETH on the hardforked chain and 4,000 ETC on the old chain.
FYI, i wouldn't hold any ETH for that long, the fundamentals are not like BTC.
Price should go down over time, not up.