Any extended deal should be a maximum of a year and represent his status at the club next season, ie backup at number 10. Whatever Alcaraz is on at the moment, that amount.
I'd personally have no issue with him staying one year as a backup option, especially as there will be no major revolution this summer. Same as Keane tbh - a year each on massively reduced wages, like a third of the current ones.
Obviously ideally we'd replace Doucoure with a fancy up and coming talent, and the same with Keane, but given they're not going to be starting players next season anyway, maybe it would be good to retain one or both of these trusted professionals, both with a good attitude, as long as the price is on Everton's terms.
If I had to choose one to keep for a season though, it'd be Keano.
Rather just directly replace both this summer though.
He's come out on Toffee TV saying he wants to be playing football, so surely he's going to be told he's got guaranteed starts next season and will be off soon.