It will outlast the cable without question. You can replace the pipes, fluid etc which services it giving it a longer lifespan.
The other option is to fit the (steering saver) to replace the brass securing nut. The benefit of that is you can get grease into the cable to keep it free and easy as it has a grease nipple! Around £50 to buy.
I'd say that may be a better option on such a size motor but then again the handling will improve significantly with "power steering"
P.s I have a very good used kit available for just £250. Costs over £700 new and it's not had much usage. Worth considering if you do switch to hydraulic.
Hope that helps
Peter @ Boatsandoutboards4sale
Peter @ Boatsandoutboards4sale ~ firstname.lastname@example.org
~ 07930 421007