If you don't want to be a partner or the firm does not see you as a future partner you should - in most instances - always move on. You will find there will be other opportunities at other firms which are far better for your career. Other firms may have a different structure, a different work/life balance or different goals and priorities which may make them a far more attractive and likely option for partnership than your current firm.

Also, there are roles in the in-house market that may present better career options - though these roles can be very competitive and demand for these roles far outstrips supply. Most of all you need to make a decision; sitting tight can stall your career and reduce your future options significantly.