Considering a bitcoin owner of large amount, and he died w/o sharing his user/pw, Are those coins can be considered as deadcoin since those coins will not circulate anymore in the Network?
Yes that has happened already and its said that almost three million coins have been lost due to such reason which has lessened the total availability of bitcoins from 21 million to just 17 million bitcoins along with one million bitcoins of satoshi which too remains unused.