There are a few rumours out there, but nothing solid:
1) Updates by October.
2) MacBook to get Amber Lake Y. It would still be dual-core, but it's possible the USB-C speed would be bumped up.
3) 13" MacBook.
This all seems pretty iffy, but nonetheless if your 2009 still works fine, you may as well 4 more months, considering you've already waited 9 years. 😉 The other thing to note is that the MacBook Pros may be updated around the same time too. It would be good to compare the specs before making any decision.