I am a fan of cctld's and even I do not think there is any chance of .com being knocked off the prime position.
What 'might' occur, and that which I think we are seeing occur, is that other suffixes are being utilised as well as the .com. This is giving the impression to some that .com is losing it's almost stranglehold at the top. This IMO is an eronious impression to hold. There are some domains in other extensions that undoubtedly would work amazingly well, memorable domains being the main ones to consider here, indeed with the correct advertising / marketing could well do better than the .com - but these are as rare as hens teeth.
This is just an opinion and it could be as right or wrong as any contrary opinion. I remember 18 years ago, around the time I started domaining seriously, similar questions as that asked in the OP were being asked even then.