If they accept LN for micro-transaction without hassle, i would spend my Bitcoin on few occasion. But i doubt i'lll something as expensive as car with Bitcoin when i believe Bitcoin price could rise.
Finally, imagine having a currency that depreciates 5% a year, such as the U.S. dollar. In the final analysis, people simply don't want to accept it, especially in international transactions. Therefore, they can use Bitcoin.
On other side, people hesitate to accept Bitcoin which is unstable compared with USD.