Well, to tell you the truth, Hal isn't dead. he will be coming back in the Green Lanturn: Rebirth mini coming up soon written by Goeff Johns. So, at least you can have Hal back. but I think you need to give Kyle a chance. He is the second best GL ever. Creativity is the key word. He's done things that Hal never did. Plus he has had some great stories in his relativly short stint as GL. Brothers Keeper comes to mind.
As far as Flash, Barry Alan died during the crisis years ago, scince then its been all Wally West who is by far, the best Flash ever. No other flash has had the kind of power that Wally has. Check out some of his trades and the current book which is one of the best comics on the market.
The thing about DC is not so much that they change the characters but that there is Legacy. That these heros move on. Some die, some just get old. Look at JSA. A great team book, that showcases the Golden age heros. Green Lanturn Alan Scott, Golden age Flash Jay Garrick, Wildcat, hawkman, and a ton of young heros carrying on the legacy of those passed on like Sand, Mr. Terrific, and Star. This is the perfect book which bridges the old and new. Check it out.