Unmaintained Dashlane discontinuing the Free plan for existing and new users

As you have already worked that out I assume you no longer use any free services that have limits or pay options? Maybe, some don't mind, as for me I'm happy to thrown money down the drain to pay for what I feel are decent software's, of course I may change my mind & move on but that surely is capitalism? So soon I imagine 'your list' will be ineffective? :p
I do use free services. And pretty much all free services I use are more than enough for my needs. Why should I pay for something if I wouldn't use the service to it's full potential?

And guess what... all the free services I use have exact same set of features and none got taken away at any moment. Companies that provide these services can count on me subscribing to their product if I'll ever need additional set of features. 🙂
No. The point is to entice free users to migrate to the pay versions because they like the product. Every single time, with every company, that's always the plan. Why would a company always offer an indefinite free version? That makes no sense. The first taste is always free, then you gotta pay.
You're confusing term free trial with free plan. Free trial is what you describe; limited time offer after which you're expected to pay for service or stop using it. Free plan, on the other hand, doesn't have a time limit and while you're expected to upgrade, you don't have to and can continue to use free plan as much as you want to.
It's for people that don't need much or additional feature of the service.

Free plan ≠ free trial
Just to declare on launch of the free service/program: it is a time-limited offer.
Exactly! This is called free trial, free evaluation period or just limited time offer.