People who buy $12 jeans aren't going to buy $150 jeans.
What happens every time a Walmart opens within 10 miles of fancy boutiques?
And the answer to your question is nothing. $150k in household income is the cutoff for the top 10%. That bracket represents 2.1% of Walmart customers. 60% of Walmart customers are in the bottom 50%. This is unusual because the bottom half spend much less time buying stuff than the top half. You still aren't anywhere near the bulk of $150 jeans consumers but no, Walmart has no impact. Target which is far short of a boutique has double the percentages in all the 100k+ and still 50% in $75-100k category.
And further the difference in living standard between Walmart customers and boutique customers is small than the spread between iPhone customers and the $150- smartphone customers on average.