I guess something between 1000 and 10.000 USD.

I don't believe it will go much higher, as cryptocurrencies have a limited market. But they can grow in their niche as online payment systems and for remittances and international transfers.

I expect a potential market capitalization of 200 to 500 billion dollars for all cryptocurrencies together. 200 bn would be roughly equivalent to a 10.000 USD bitcoin price, if BTC manages to keep its dominant position in the cryptocurrency market.