ASP Developers turn to .NET and use Expression Web2 if you are looking for serious Web Development.
Every company has tools for specific language for a reason. Why bother updating both asp and php code when microsoft has overun ASP.NET with a perfect tool?
Not to mention the extensions existing on it. Do you know how much development time takes to make a product compatible with PHP and same time ASP ?
It is not worth it if you are trying to be popular for particular category of people aka php where most developers use and want wizzards.
And yes also WebAssist had announced that new products wont support ASP and if i am correct DWCS4 has no ASP or very limited ASP support and next release they wont have any at all for dynamic development.