Essentially you are asking me to volunteer relationships that are usually in a somewhat fragile state (i.e. valued but undermaintained) to some impersonal external system that's going to send growth-hack-like e-mails to them and ask them to download apps.
How about something more akin to a personal CRM app where I could unilaterally enter some of my friends and it could help me maintain engagement through reminders or scheduling assistance (or say, location awareness?). I would have downloaded that in a second, and I would posit that a lot of others would as well since most people strongly identify with the "people I wish I had kept in touch more" message.
Monetization might later come in from the business angle to the same idea (maintain engagement with valuable contacts, using only an app).