Where screen scraping is concerned, do you have any thoughts on the risk of it turning into an arms race between you and companies with valuable customers as th

Where screen scraping is concerned, do you have any thoughts on the risk of it turning into an arms race between you and companies with valuable customers as they try to prevent you from making migrations (to them, poaching their customers) easier? - e.g. They make it hard to scrape by deliberately and systematically changing their pages frequently forcing you to adapt regularly. It strikes me as though the economics of this are not in your favour as a particular company only has to worry about their own site, but for your business model you potentially have to fight a war on many fronts to keep your service valuable and functioning.