Not if the new timechain coins are an income event, e.g., let's say you have 1 btc presently and there is a new fork the presumptive initial price of both forks will be equivalent which means the new fork will be considered to be an income event equal to 1 newbtc so if its 95k, you just "earned" 95k and will have to pay income taxes on that new coin requiring you to sell it immediately before one of the forks starts to go toward zero or risk being unable to sell to cover your income event. This is separate and apart from realize or unrealized gains, I suppose if it goes way down the realized loss might offset the tax consequences of the original income event. Im not a tax lawyer but its something Ive been thinking about.