It doesn't take conspiracy theories to assume that prices are going to go up. Even ignoring inflation, there is a strong possibility that prices will go up simply because the priorities of management changes.

Let's assume that the motivation is to increase profitability. There is nothing mysterious about that motivation because businesses exist in order to make money. There are a number of ways to do that. One way is to increase volume without changing the profit margin. It works well when the company is still growing. A second way is to increase the profit margin by decreasing costs. There are many ways to do that: increasing worker productivity; using automation, when it is cheaper than labour); or selling goods that have higher margins (presumably ebooks fit in here). The third way is to increase profit margins by increasing the price of the goods sold.

Once again, grand conspiracies to knock out the competition then raise prices aren't necessary. You simply have to understand that the motivation of businesses is to make money.