Even if the fees will be 1/2 or even 1/4 from what they are now they would still be too high for daily usage. Imagine you would have to pay 5-10 bucks every time you buy something with your credit card. I don't think Segwit and LN would decrease the fees to less than 1 USD, so even if bitcoin sustains, there is surely a room of alts to take over in areas where using BTC will simply not be worth it.
Not sure how you derive your fee analysis.
Don't forget that Lightning Networks enables atomic swaps with the other segwit and LN coins like LTC, VTC and MONA so if BTC remains too expensive, these other coins will greatly benefit from it.