In any case, the long-term solution for true openness is to be able to run open-weight models locally or through third-party inference providers.
The reason to subsidize is the exact reason you are worried about. Lock in, network effects, economies of scale, etc.
I mean, this is the playbook of every tech company for the past 30 years. You sell something at a huge loss to gain market share and force your competitors to exit, and then you begin value extraction from your, now captive, customer base. You lower quality, raise prices, and cut support, and you do it slowly enough that nobody is hit with enough friction at one time to walk.
If you expect anything else, I don't know what to tell you. This is very much the standard. In fact it's SO much the standard that companies don't even have a choice. If you choose not to do this, then the people who are doing this will just undercut you and run you out.
The key piece in this is that, once the value extraction begins, it can't just strive for profitability. No, it also has to make up for the past 10 or 15 years of losses on top of that. So it's not like the product will just get expensive enough to sustain itself like you'd expect with a typical product. It'll get much more expensive than that.