Are you going to use polonoiex accounts as storage wallet for years ? There will be no guarantee that they will be into business when you will come back. One recent example : directbet.eu, they were the market leader in gambling industry, suddenly announced permanent termination of their services.
Where did you read that directbet.eu site is closing down, recently i have used their service and i am able to bet on that site without any problem and bets are getting settled
If you want to store coins in poloniex that is not advisable as if the site close down then you dont have control over the coins in that exchange as you dont have the private keys of the wallet address which you are holding coins in poloniex