While Spudstr is completely wrong about named-based virtual hosting being required by ARIN at this time, he does bring up a valid point.
As IPv4 space exhaustion comes, it will happen sooner or later that having a uniqe hostname for a website will not be proper justification for IP's. What will happen then, will be something like...
#1. Hosts will simply start charging a lot for IP's, hoping to curtail usage enough to have other justification hit the magic 80% rule. This may or may not be effective.
#2. Hosts will simply lie to ARIN and say every site is SSL. Many will go as far as to setup actual SSL sites for each domain, just to "prove" that indeed this is needed. I expect this to pretty much be the defacto standard in the adult industry, as when there is a shady way to do something pretty much everyone follows it. :/
#3. Hosts will just run out of IP's
Every time a customer asks us for a unique IP per site for SE reasons it pains me. This is complete IP space waste, as there is really no reason for it. If SE's do indeed penalize sites sharing the same IP, then they are having by far the single largest effect on unnecessary IPv4 space waste that I am aware of.
Our policy is to give out unique IP's for each site if a customer requests it, no questions asked. This is absolutely currently within ARIN justification policy. However, ARIN has already asked us on multiple occasions why individual customers seem to have diverse allocations out of multiple blocks, where the allocations are extremely small. I can guarantee there will be some form of means to put an end to this allocation policy within the next few years.
I guess my point is to make hay while the sun shines? As a techie, it truly pains me to see. However, some day in the near future this may no longer be a valid means of conducting business. If you note ARIN policy, a lot of scrutiny is already being placed in this area (e.g. when you apply, they require you tell them why you are not using name based virtual hosting 'for their records'), so the writing has been on the wall for a long, long, time.
Good luck!