Spares and Maintenance
With the possible exception of Cessna, I think every manufacturer of light aircraft has in the past been bankrupt a few times, is currently experiencing difficulties, or will be in difficulties in the future when the investors decide to stop funding. Or when the R&D department overstretches itself and tries to bring to many types to the market simultaneously, or when the customers lose interest because there's not enough different types available from the same manufacturer (so no growth path), or when the engine manufacturer goes bankrupt, or when the FAA/CAA/... forces a complex AD on the type, which the manufacturer has to fix under warranty. Or something else.
So if you're going to base your purchase decision on the expected continuity of support from the manufacturer, you may find yourself limited to flying in the back seat of a Boeing or Airbus only.