Dash no, but XMR and SDC are real alternatives to BTC
A real alternative needs to have :
Focus on user-friendly usage (this means having solutions into place for Android, iPhone, Linux, Mac and Windows users or it will never get mainstraim usage)
Scalable with its transactions / users
Speedy transactions
Private transactions
Fungable as cryptocurrency
Focus on Reseach and Development
And frankly it needs to have them all in order to form a real alternative to Bitcoin.