If I understand it right, You synced your contacts to google account. Is it ??
If yes, the contacts are safe and when u change your mobile, all u have to do is login to google account from the new mobile and the contacts get auto synced to your new mobile
All i want to say is that if you have synced your contacts onto your google account, they will be present in "my contacts" folder in your gmail. You will have to check this in your desktop or gmail opened in desktop mode from the browser