.COM is the only commercial extension. Most of the ngTLDs are for utilitarian purposes to suplemenet .com. Such as .support, .tech, .forum. But none are meant to completely replace .com. Their purpose is to create a direct link to a specific section or a complemantery location of the main brand. The only exception is ccTLD domains, some of which have found alternative uses to .com. But .com will never be taken over by another extension. Any startup or company using anything other than .com will be viewed as inferior and will have an uphill battle. Unless their customers are local and they are using the right ccTLD.