Every tech company who offers incredibly generous free stuff eventually does this, even Google. There's no free lunch. All the cloud storage, the dev salaries, the bandwidth needs to be paid somehow.
I remember when Google was offering unlimited photo storage in their Google Photos cloud. Well that's been gone for a while now, even for the Pixel users who were supposed to get this indefinitely.
Remember Cerberus for Android? They had a "lifetime license" you could buy at one point and after a while they revoked that with a sobbing email saying their business doesn't work without users paying a subscription and they'll have to move everyone, including those who paid the lifetime license to the subscription model, to not go bust. Fuck them.
I think enough users have been burned so far by this model:
Step 1: Start-up launches cool new app with amazing free feature to gain market share, even though it makes no sense how they're funding it all with nobody paying for it.
Step 2: VCs see the amazing user growth and invest.
Step 3: Business or lack thereof was unsustainable from the start so VCs start clamping down, shutting down free accounts and squeezing paying users.
Step 4: Business slowly dies out since it was never sustainable, and users leave to greener pastures as they see the freebies being taken away from them.
I wish tech companies would be sued for backtracking on their promises they made just to lure users in to fake growth.
Nowadays we have new laptops with routinely 1TB of storage. Imagine 50GB of free storage with Dropbox, or any equivalent, today.
Unless you buy Macs which still start with 256GB storage.