I agree that the world economy is sliding down - wages are stagnant in the US, UK and much of western Europe, China is having problems selling so much stuff to the west because there's no money there. I think the value of Bitcoin will rise as the value of fiat currencies go down. As always the best advice is to hedge - own some fiat, some gold, some Bitcoin.
Nice point. Diversify your investment portfolio as commodities / crypto currencies / fiat money. But not only Bitcoin, you can buy other promising crypto currencies that fell down at the current times.
I think that the world economy is sliding down due to geopolitics. The powerful countries rival on the diplomatic arena and protect their markets from the enemies, therefore the volume of transnational trading decreases. Probably, this factor gives a negative impact to the world economy.