if I send very low fee (0.00001 BTC), how long it take to confirmed? will it ever be confirmed?
If its a few days to confirm, its still fine
Is it possible to accelerate such a transaction later so that it will be confirmed? or will the transaction be destined to return to original wallet
Hmm, yes. It will be confirmed but can take days, weeks, months.... or just one hour ... you never know, nobody knows. Few weeks ago my 4 satoshis/byte tx was confirmed within day ... that time was less than 15k waiting transactions
to accelerate tx use free
https://www.viabtc.com/tools/txaccelerator/ or paid version
https://pushtx.btc.com/If you do not need quick transfer (like moving them between your wallets) go and try it. At least this lowers the fee average. BTW You know why fees are so high? because we (users) are hungry to make quick transfers, thus offering them. If everybody would use lower fee we all would be happy.( I'm pretty sure miners would adapt )
You can also enable replace-by-fee function (if your wallet supports it)