Not even close. The 2 best selling home consoles of all time are both Sony consoles, and neither of them gained any benefit from the internet either, so in a world with no internet, the PS1 & PS2 still would have dominated. There's no reason to think the PS4 wouldn't have dominated either.
I would have to agree. Out of the big 3, the internet has helped Microsoft the most, which means the internet has hurt Sony. Without the internet, Microsoft would have to have found another avenue into console gaming.