However, poloniex is still able to provide 0.0001 fee withdrawals (which merge a lot of payments together, while having overall 400-500 sat/byte fee, resulting in 0-1 block delay confirmation)
My question is, are they any other (centralized) how wallets where I can keep small amount for daily usage (payments in the range of a few mBTCs)?
I know until recently xapo had free on-chain tx..but now their fees is also in the 0.0005-0.0009 BTC range, which is impractical for $2-5 payments.
The only option that I can think of right now is indeed poloniex. I remember thinking that they charged quite high withdrawal fees as you know coinbase, and other bitcoin exchanges processed withdrawals free of charge at the time.
However they are the only service still providing the original 0.0001 btc withdrawal fees, but you do have to be very careful as they might run on a fractional reserve and some day have liquidity issues.
Don't forget Mt Gox....