“What’s next?” is on the tip of everyone’s tongue in this industry. People are always hungry for what’s going to replace what exists now, but from a social platform perspective, we’re not in a here today, gone tomorrow ecosystem. Instead, platforms are “stacking” on top of each other. They’re not being replaced, just added to.

Facebook has, at least for the time being, established itself as the social networking leader. Its dominance has been in place for some time, and despite the predictions that Facebook will be replaced by a “counter-point” (a.k.a. The Facebook Killer), Facebook’s dominance has continued.

Instead, Facebook is being stacked upon. Facebook took what other social networks like MySpace and Friendster were doing and solidified the social graph trend, which is essentially people building, maintaining and managing their personal relationships through technological channels. Facebook unleashed the social graph to the world. Today, more than 900 million users are maintaining their personal connections through the platform, and this shows no signs of going away.

Instead, Facebook’s social graph only continues to grow stronger. We’ve seen the introduction of the location-graph through social platforms like Foursquare. These platforms can feed into social-graph focused networks like Facebook to add geographical context to what the social graph already provided—a platform stacking onto but not replacing another platform.

Now we’re seeing the next evolution with platforms like Highlight and Glancee bringing the interest and location graphs together to create offline experiences. Things seem to be coming full circle Relationships moved online with Facebook, translated themselves into something more real-world through geo-location platforms like Foursquare and are now moving offline again through Highlight, but all of this is happening together. Not a single platform has replaced the other. They’ve simply stacked on what others were doing.

However, a hiccup does exist. As online moves offline the digital courage that existed before goes away, and a permission disconnect occurs. Connecting online brings a sense of comfort because of its seemingly transactional nature. Highlight makes the transition from online to offline very abrupt, which can be off-putting. Without the right permission controls in place, the stacking in this form, at least, might end.

It’s interesting to see all of this occurring. Will we see something go away to be replaced by something else, or are we heading into an age in which social media moves from being a set of separate platforms to being a sum of its parts?