I may be wrong but it looks like in the long run, the only advantage of LTC for most people would be that transactions are faster than BTC.
is there any way that BTC transactions could be made faster in order to compete with LTC for buying stuff?
That's the most irelevant difference between LTC/BTC.
LTC will provide diversification and that's why LTC might be even 1:1 on BTC. When some big players move at the only crypto it generates vola and panic/greed. Too much vola makes a currency useless.
On a multi crypto enviroment panic sellers can move to the alternative crypto(s) and the overall market vola on crypto stays lower. But don't worry, one 50% less volatile bitcoin at 30% market cap is definitively more worth than 1 BTC of todays 95% cap.