I'm so sorry for your loss. I'll be honest, I have no idea what his natural lifespan would be, & I'm sure it varies by species too, but it's always sad to lose a long-time friend, even when you should have had much more time together. He sure was a handsome fellow, & I'm sure he'd want you to go ahead & give the very best care to Gill & any other animals you're keeping. Even though the timing was terrible & you miss him greatly right now, I think you'll find that there will be others that are very special in your future- at least, that's been my experience over the years.