At some point in time I guess it will become either one thing or the other. It cannot stay both at the same time. Can it? Is it a healthy usage method to have it as both?
That's a good question. Of course, they can be partially both with the vast majority using it for one of those things. Nowadays, bitcoin can be used for payments, but is mainly used as an investment. In the long run, however, I think that the payment method needs stability, because otherwise nobody would bother to take the risks or convert everything to fiat on weekly basis, you know. The best thing would be if bitcoin stabilized pretty much forever on a reasonable price (at least the ATH one) with regular 10-15% price fluctuations. This would be something merchants could live with and traders could profit from.