Existential deposit is currently 0.01 DOT (old). It will be 1 DOT (now). Many people will be confused why their transaction failed due to existential deposit. People cannot send <1 DOT to new account, account with exactly 1 DOT won't be able to make transaction. Currently the tx fee for a transfer is 0.000149 DOT (old) or 0.0149 DOT (new), so I will suggest to make new existential deposit to be 0.05 DOT (new). The primary reason of having existential deposit is to prevent dust account and with whatever DOT price, I wouldn't consider 1 DOT (new) is a dust value.