A business with potential millions of users will need millions of SP to continue. They need these SP to claim new accounts to onboard new users. They may even delegate a minimum number of SP to users to function in their DApp to earn tokens. DApp will have their own incentive to buy/hold millions of SP to support millions of their users. The only missing thing is the killer idea for such DApp..

It will take some trials and errors from newer DApps on Tribes or SMT. Due to sheer number of attempts, one or few DApps can be a big hit that will bring millions of users who will require SP/RC to operate.

Users of that DApps might not be aware of the underlying Steem blockchain. DApp can provide necessary SP (e.g. 20 SP delegation) to new users to function in their DApps. In that case, that successful DApps will require millions of SP. The killer idea for that DApp is still to be seen: right now, @actifit, @steemhunt, @sprinterlands, @palnet, @steemleo, @dlike, @threespeak have good possibility to onboard millions of users.

More discussion: https://www.steemleo.com/steemleo/@dtrade/ask-steemleo-and-steemit-what-type-of-new-dapp-businesses-or-better-model-of-existing-businesses-can-bring-10s-of-millions-of