There are several fairly clear-cut career paths for a project manager, these are:
Programme (a series of interrelated projects) management
Product or product line management, i.e. carrying a responsibility for development of a product or a line of products
Functional management (heading a certain business function, i.e. software development or research and development etc)
And when all the way up straight to the board level. However, you've got the beginning of the "non-technical" ladder wrong, especially when talking of a business where information technology is not a core breadwinner, but rather an enabler (these make up for majority of software development jobs).
Within such a business non-technical ladder starts in the trenches, not at middle or senior developer level. Normally the first step is a very junior position that requires little or no formal training: call centre agent, sales person, general admin etc. Since the pay is low and the staff churn rates for these jobs are very high to motivate the troops management tries hard to create promotion opportunities.
The management very quickly runs out of call centre team leader and senior sales executive positions, since naturally there are not so many of these in comparison to the number of “soldiers” and once people get promoted to that stage from the trenches they tend to stay for longer, often for years in the hope of the further career advancement. Hence the cross-functional promotions begin with sales juniors spilling over into IT.
Here since they suck at the actual technical work they assume the positions of business support and test analysts. From there ex-sales junior can progress either onto the technical ladder (become a junior developer or start building some automated tests) or carry on into BA and PM. Many of them even give it a try, however since the technical work requires a lot of hard-skills, training and not regarded highly within non-IT organisation's hierarchy most of them move on into business analysis, then project management and so on with many of them eventually becoming “Head of IT” or taking responsibility for some other function within the business. They might even put a “programmer experience” on their CV, although they never delivered anything more complex than a VBA script.
Developers are completely different animals. Every business values their good developers (middle level up) since they are business technology experts. And the technology is meant in a very broad sense, starting with a domain expertise and ending with the deep knowledge of concrete systems that make the business tick. Good developers are very difficult and costly to replace, much more difficult than a project manager or business analyst.
Hence there is a chasm between a senior developer and any other non-coding roles (i.e. project manager, business analyst etc). There is always a shortage of good developers within a business (availability of good developers being the common limiting factor in speed of evolution of in-house software) and usually the organisation just cannot afford promoting people who can and actively code into non-coding positions. They can make you a team lead, but then eventually you’d be expected to do your coding norm anyway.
It is a paradox, but it is just so much easier to jump across to the non-technical ladder being a mediocre or junior dev, rather than a fully fledged techie. I guess that’s one of the top reasons why technically astute people from run-of-the-mill IT departments eventually move onto freelancing.