Ideally i think downtown would be the best place to open a store like H&M. It's relatively in the center of the city, plus its easier to get to from outside the city than Stavanger. Its got better flexibility and store size than the Avalon and Village mall. Plopping a store down like it would raise the bar for competition, letting even more commonly known stores from the mainland to set up shop. Plus the growth of customers in the area would benefit all the other businesses as well.
I know for a fact kids my age would be able to take on a bus ride or two if it was necessary to get to a great store like that. Also, I'm sure people would be glad to go outside of the dark and dirty Avalon and Village malls to have the experience of shopping downtown for a change.
I did some research on the properties subject and most sources said that H&M uses buildings with at least 15,000 sq.ft. The H&M website itself proclaims that they only rent out properties to flex and adapt to the market. So properties like this
http://is.gd/5KKZX2 would be perfect.
The only outstanding problems I see with developments like this down there would be the need for more parking and better transit, which we're all begging to be solved anyways.