Competitors will emerge sooner or later and today, it seems that BU is challenging bitcoin. BU may compete with bitcoin based from what is happening today, the fork ,etc. That is in the digital world. On the other hand, if we speak about the competitors of bitcoin in the real world, the worst enemy of bitcoin is no other than the government
It could also become its best friend (sort of)
And I don't mean that the government (any government of a major country, at least) is ever going to let Bitcoin openly compete with a national currency, that should be as clear as day. But the government can still greatly help Bitcoin if they choose to ruin their fiat currency which does happen now and then, here and there (see Zimbabwe as the most glaring example of this kind). Previously, before Bitcoin, the common folks of such a country couldn't do much. They could use, say, US dollars as cash but the government wouldn't allow a foreign currency to substitute a national one in any meaningful degree since it retained control over currency circulation via banks. This is no longer the case with Bitcoin which can be used for money transfers just like any other non-cash currency but doesn't need banks for that