The evidence is that X is pushing further with Grok its AI chatbot and in developing a version of Grok that is going to be free for a less than fully paid-up user of the platform.
X is pursuing a beta launch of Grok in free, "freemium" version, which shall be available to all users. This shall open up major further usage on its generative AI tool.

Because today, very few people can access it. Grok is only available to X Premium subscribers at the moment and given the 1.3 million people are paying to use the app, about 0.26% of X's user base, that means Grok usage is very limited. Therefore, there is not a heap of insight yet into how valuable an addition that actually is, isn't, within the broader X experience.

A free version, though restricted usage for non-paying users at least makes more people try it and could induce even more X Premium sign-ups. That depends, of course on how many people want to generate images to go with their posts, or indeed, generate their X replies entirely. But the only way to ensure that many people will find value in it is by giving them access, and then X can get a better feel for how much potential there truly is in that respect.

And that also would help the parent company of X, X Corp, obtain critical investment in its offshoot xAI.

XA I, the "non woke" generative AI project founded by Elon Musk in order basically to get back at OpenAI, the company that he helped to fund in its early stages before being ousted from its leadership team, is the project through which Musk hopes to make a more significant element of his business empire and a key challenger to his now-rivals. xAI has raised $6 billion in funding so far. It is possible that this can help support the X app itself, where xAI may enter into some sort of deal on data supply with X, forcing some of that money to flow between the two companies.

As such, xAI's success is very closely tied with X itself, which is still struggling to get its business back in the black. So getting more people to use Grok makes ever more sense, while xAI has also built a huge AI supercomputer cluster, called "Colossus", to fuel this effort.

All of this requires ongoing funding support, and for the xAI project and X itself to remain alive, both must be able to demonstrate their concrete value to their proposed partners. Which again speaks to maximizing Grok usage as an important step - so it's no surprise in and of itself to see X consider a free access tier in an effort to boost usage.
While it's interesting to see whether Musk faces any conflicts in those due to his coming role within the Trump administration, xAI has for example already received significant support from Saudi Prince Alwaleed bin Talal, a partnership already questioned on national security grounds. Of course, Musk heading in charge of reviewing government departments dealing with AI, foreign investment, data security, and so on would present a huge conflict, and Musk might have to recuse himself from such or stand down from his businesses.

How interesting it will be if the Trump administration tackles this aspect and how this then becomes associated with development and funds for Musk's ongoing projects.

Either way, it makes a lot of sense to give Grok greater exposure and seems now X is taking the lead on this.