@Mickman,
I guess you are one of the guys who don't mind living under a high voltage power line and who will but a mobile phone mast on their rooftop
You are right, everything is possible with wireless, it only depends on the RF emittance your wireless device uses. After all, you could X-Ray a concrete wall
NO future wireless device will be capable - for obvious technical reasons - to reach every corner of the house by using enhanced algorithm to transmit more data. Ensuring full coverage, no matter what the building material is, can only be established with higher emittance output. Ask an physician and he will explain better than I do.
Wireless is an excellent addition, but if you do build new wire is the way to go. And there again, use the best product on the market today as the house is build for the next 50 to 100 years. Using plain old Cat5 - which is an industrial standard of the 70th and was followed by at least 5 new standards by now - is not future proof and not good for multimedia application in 20 or 50 years. So the better the quality today the longer you will be within new technical developments.
Just consider that not only the EU but also governments are tightening regulation on RF transmitions for domestic use. SO the better you protect today the better you protect yourself and your family in the future.
Just my few ct's of thoughts
I like Wexfordman's link to IrishHomeNet.