I'm all over the place, use the phone for everything now, laptop just sits in its case, collecting dust in the corner...I'm butting right up against 5g a month...
Even though I am on the 'unlimited' plan, I try to use WiFi wherever possible to keep my data usage down. Like at home, hotel networks, some airports, the client network, etc.
When I am traveling every week on business, I end up using about 3.5 GB a month. When I am working from home, I am on WiFi and last month used only 150MB.
Current customers who were locked into a contract on Verizon Wireless will be grandfathered into the Unlimited Data plan forever, but it can change if you change your phone number, cancel service, suspend service, or don't renew your contract. Upgrading doesn't affect this.
I think as long as you had the unlimited data before July 7th, you should be okay. You can also download the Mobile Data Tracker or 3D Watchdog to make sure you don't go over your limit.