Marvel Girl is one of the first X-Men to be recruited. By her real name of Jean Grey, she is a mutant with the powers of telekinesis and telepathy. I don't think she should be killed off. If she's gone, then the original X-Men will be incomplete. Also, I don't think Rachel Summers should exist either. She's an insult to Jean Grey and to time (since she is from an alternate future timeline).
If I get the chance to work on X-Men comic books, I will bring Marvel Girl back to life if no one else has (hopefully, someone will). If Marvel Comics is trying to re-introduce the X-Men the same way DC Comics did with their characters after the Chrisis storyline, I will include Marvel Girl in the comic books.
I will include this character in video games when I get the opportunity. She will have an interest with Cyclops, however, she doesn't get along with Wolverine. Therefore, Wolverine pushes her around and lectures her.
As shown here, I thought of giving Marvel Girl a uniform since she made her first appearance with the original X-Men.