I do not see them killing the free plan, even Salesforce knows better than that. I bet they'll run it very similarly to how they run Heroku, and the Slack integration will get better. But prices might go up too.
LOL, having worked with SF for the last two years I can completely see them killing the free plan. They care only about licensed seat count, at ALL COST!
Yeah they're like baby Oracle.
The founders came out of Oracle so it's the same playbook.