They are already with Ivy Bridge. We won't see Haswell quad-cores with less than 35W TDP..
Haswell has adjustable TDP.
Ivy bridge will not be much of a performance increase. The ordinary dumbo user will not notice the difference between Sandy and Ivy bridge.
Heat with the Sandy bridge models are an issue - I have noticed quite a number of postings about logic boards failing just out of warranty. Am glad I went back to a 2010 server.