The main point to consider would probably be whether castration would result in loss of your sexual feelings, which are now driving your desire to live as your wife's submissive cuckold including your desire to submit to her feminizing you.
From this point of view, your wife, and your relationship, and you as well, would probably be better off if she were to require you to wear a male chastity device and (of course) become your sole key holder. Your continued obedience as her submissive and feminized cuckold will then be guaranteed by your continuing desire to please her, thus gaining occasional release from your cock cage so you can masturbate — or so your wife can fuck you (her choice).
An additional consideration would be: castration.... as I understand it.... tends to result in loss of muscle tone accompanied by weight gain (not in good places) — associated, apparently, with loss of testosterone. If so, that would result in you becoming physically less attractive and less capable of performing tasks your wife assigns to you.
I suggest a better alternative, in addition to your wife requiring you to wear a cock cage, would be to order a copy of Janice C. Parker's book, "My Husband Is My Maid," then present it to her as a gift — and... with your wife... proceed accordingly. It can be ordered from online sources. See, for instance:
My Husband Is My Maid by Janice C. Parker
You and your sexy wife seem already to be well-along on this, or a similar, path.