Why would anyone go to Dalkey for shoes? - There is not a strong retail presence in Dalkey: it is mostly convenience and food, so you will not get customers going to Dalkey to go clothes shopping. Also, I believe that specific purchase retail units have not done well in Dalkey historically. Has your friend looked at shoe shops in Greystones, Malahide, Glasthule which are similar in market positioning and demographic?
It's my opinion that specialised clothing retailers(ie shoes, hats, accessories, high end clothing etc) will only work in the smaller villages / areas around Dublin if they have a very strong USP (Unique Selling Point) this can be a particular brand or very good pricing or a certain clientele.
BTW I am not in the shoe business, nor am I retailer nor am I female! - but even as a man I wouldn't go to Dalkey to buy shoes - I'd go there for a pint or a meal but not shoes!