Bitcoins still maintain a significant market share when it comes to cryptocurrencies, but some altcoins came up giving it a run for its money.
Given that altcoins come with improvements that the bitcoin lacks, bitcoin developers maintain a high level of innovativeness to ensure that it continues to stay at the top of cryptocurrency trading.
There is always the chance of technical and economic flaws causing bitcoins to die off catastrophically. Altcoins continually work on addressing these identified flaws to create marginally stronger digital currencies. Also, consensus flaws could lead to the bitcoins natural death.
While bitcoins, with community desires, can add utilities similar to those found in altcoins, most cryptocurrency traders prefer to put their trust in a tried-and-tested model rather than having it incorporated as a test drive.