Perhaps the most surprising thing about succession planning in the advisory business is that 75% of all firm owners claim they have an exit plan. That percentage seems high, so a bit of review may be in order.
The 75% number comes from AdvisorBenchmarking, which claims that "a full quarter" of principals don't know how they're going to retire and "more than one third" don't have a firm timetable for doing so.
Whatever the timeframe, advisors can package their business for sale if they've got a few years to think ahead -- although over a decade to build a succession plan and ultimately an exit is better.
As always, the more systems you can build into your practice, the easier it will be for you to disintermediate yourself from it when it's time to go. Systems are what prospective buyers look for (unless you're selling yourself along with your book of business), so an office manual is crucial.