The answer to this question lies in the biological and social roles of males and females and in the way that sex toys may replace the role of men in those relationships.
Simplifying the subject considerably, evolution has resulted in most species having males and females for sexual reproduction resulting in the sharing and diversification of the genetic pool. However the existence of two 'versions' of a species has also allowed the development of specialisations/roles for the males and females.
In mammals the main biological difference is that the male provides sperm and the female provides eggs. After fertilisation the female has the role of looking after the embryo in the uterus (womb) and providing milk to the offspring after birth.
With this simple view the male provides only the sperm and a widening of the gene pool. However it would generally be too expensive in resources (in evolutionary terms) for that to be the only role of males, and so social responsibilities have evolved. Males often look after their mate and offspring by helping to provide food, protection and a 'home'.
With humans, changes in much of the world mean that many of these social roles can be provided by women alone and some women argue the world would be better off without men. Additionally biological advances may make men unnecessary for their biological role of fertilisation of the eggs.
The last remaining need for men might become one of providing entertainment and sexual satisfaction for women - but perhaps women could do without men for sex!
There is a growing move towards women turning to other women for sexual relationships; women are using sex toys more often as penis substitutes and many women find they get greater sexual satisfaction from sex toys (as measured by strength, frequency and reliability of orgasm) than they do from sex with men.
Some women act out the male role by using a strap-on harness and many dildos represent a man's penis. On the other hand many women prefer to exclude the male phallic image from their sexual play and they choose a vibrator or dildo that is not phallic and may indeed have a distinctly feminine design as does the vibrators you can find HERE.
This simple picture, though perhaps frightening for men, is rather too much of a simplification. Many women have a psychological need for men as a partner in life and sex (as men do for women). Probably for most women this will always be the case. These women usually also enjoy sex toys, using them both on their own and with their partners to get more satisfaction and enriching their relationship.
If women as a whole could choose whether men existed or not I feel sure they would come down on the side of keeping them. However if some other reason arose why men had become undesirable then women have already shown they could do without them quite easily ...