Hmmm. Seems I needn’t fear getting trampled by the mob charging forward to give their various answers to the question! 
So, feeling like I’m in a safe space, here’s how I speculate the next few decades will unfold. The whats and the whys:
1. What: Institutional egalitarianism will consolidate its “establishment” character. This means that in seminaries, mission boards, denominational leadership and quasi-denominational associations, and publishing media of all sorts, egalitarianism will be enforced. Anything less than full-throated egalitarianism will be deprived of vote and voice in all these institutions.
Why: This is the trajectory in both secular and religious feminism. At first feminist voices demand “a seat at the table, in the name of simple justice and equity.” They are granted such. Once they have the levers of power in their hands, the same feminists refuse a seat at the table to any dissenters. Any who don’t recognize this pattern in the culture at large or within various religious contexts have spent the last 50 years with their heads deep in the sand.
2. Complementarianism as a viable agenda will completely disappear.
Why: This is where Renn makes his best prediction and validation thereof. In a nutshell, he claims (rightly, I think) that the complementarianism that had its origin in CBMW and its leaders (Grudem, Piper) has failed to produce a second generation of scholars, thinkers, and writers to defend and develop the basic complementarian thesis. CBMW is a think-tank without any thinkers, or thinkers-in-the-wings.
3. Christian egalitarian women will find it harder and harder “to kick against the pricks.” They will find that Christianity is progressively abandoned by males - even more so than is evident today - and their egalitarian convictions will grind painfully against the various temperaments, talents, and drives that are hard-wired into them by the fact that they are created as females.
Why: Creed and creation are meant - by divine design - to complement and mutually energize one another. When they are in conflict with one another - as they are in any outworking of feminist dogma - the feminist/egalitarian lives in a constant state of interior conflict and confusion. The pain resulting from this conflict can only be diminished by one or the other making a retreat of some kind.
Sometimes the egalitarian/feminist forceably diminishes his/her essential sexuality. Women become manly. They behave as men long enough to become essentially mannish in their nature. Yes, genetically they are still female, but spiritually/psychologically they become progressively bent, warped, their sexuality so marred as to become difficult to discern any longer.
Or, if the feminist creed is to retreat within the soul of a feminist, then the feminist adopts all manner of hypocritical postures and behaviors, or otherwise refuses to live out the implications of the egalitarian creed. The best thing, of course, is for the egalitarian to “get woke” and to seek out some non-feminist creed to guide him/her in his/her life as a sexed creature living in relationship with both sexes.
What I describe in the preceding paragraph summarizes the primary “attraction” for the educational materials whose development and distribution I have overseen for the past 30 years. The largest population to respond enthusiastically to what we produce are women (1) who have despaired of the feminist “vision” and abandoned it, looking desperately for something that actually works for them, or (2) younger women who have seen their feminist mothers’ lives crash and burn, concluding it was their feminism which did their mothers in.
What I have witnessed over the past 30 y ears, particularly among Christian women, is likely to be replicated throughout egalitarian evangelicalism in the next generation or two. Said another way, if complementarianism today is breathing its last breaths of credibility, religious feminism will be doing the same 20 or so years from now.
And, so, what will “follow” complementarianism?
The only valid possibility is a full-throated, nonapologetic, comprehensively Biblical patriarchy - both in terms of a full-orbed theology of the sexes and also in terms of viable communities where Biblical patriarchy governs cradle to grave life in those communities.
I say possibility because I see nothing yet on the horizon to suggest such a development will emerge. Remember, those who did not worship Baal in the days of Elijah were so few in number and culturally invisible that Elijah thought he was the last YHWH worshiper left. Yes, the gates of Hell will not prevail against the Church. But, that promise says nothing about how numerous or effective the Church shall be at any given period of history.
Okay. I’ve stuck my neck out.
Are any others brave enough to hazard an opinion on what comes after complementarianism?