Personally, I think that when Bitcoin is finished, another coin will come to replace one coin. But for the time being it is too early to talk about it since Bitcoin will end in 2045 and this is more than 20 years old and can change everything a thousand times. Since we are living now and it is necessary to act at the moment for this, all efforts should be directed for our well-being. We can only wait and gain patience and we just need it. And according to forecasts, Bitcoin should grow to 50 thousand dollars, which is of course an impressive amount.
since Bitcoin will end in 2045 and this is more than 20 years old
What do you mean exactly? Maybe around 2140 when Bitcoin will reach his total supply? But this doesn't mean Bitcoin is finished, there are still miners to confirm all the transactions. Remember: if you do a transaction you have to pay a transaction fee. This amount of BTC is for the miners to confirm your transaction. 