I mean, I get what you're trying to say but in no way does a paid subscription "promise" they'll be around any longer than if they were free. Sometimes transitioning from free to paid can backfire and actually shorten the lifespan of a product.
Transitioning from free to paid can backfire if you depend on the free users for some critical way and gitlab is leaving all that untouched.
They're charging for extras such as support and CI minutes, both of which are features that usually will be of use to corporate customers.
All in all I see this as a positive move for gitlab in the long run, lack of revenue streams was something that bothered me and made me wonder about their long term viability. For me at least those worries are now gone.
EDIT: My knowledge of their pricing is inaccurate. I thought EE was one-time on-prem charge.
But more is better.
They're in no holds barred exponential growth territory and I don't know the ratio of corporate customers:free customers but I suspect that the free tier is growing faster. So they really need more sources of income, and preferably b2b ones.
Companies like gitlab become mission critical for the customers that depend on them (one reason why github (not gitlab) is now in the 'too big to fail' category, if they were to go under there would have to be a rescue operation of sorts).
Gitlab has a narrow base and broadening that base is really good.
GitLab.com has become increasingly popular over time and we want to continue to not only provide a great self-hosted product, but also an amazing hosted (SaaS) solution.
Note that the above is tricky. There are revenue streams that lose money by the books, but are worth having because they help something else. An example is a store sells milk at (or below) cost because people come for the cheap milk and buy lots of other things.