Walmart will likely face stronger headwinds as time goes by.Walmart (WMT 0.19%) has risen from modest beginnings in rural Arkansas to grow into one of the world's most successful retailers. Although its rapid growth days are likely behind it, the company has continued to earn significant returns for investors as it leverages its massive U.S. footprint and online presence to cement its leadership.However, Walmart's stock has become increasingly expensive, and it continues to face intense competition from oth ...