Abrasive water jets have their niche markets where they can outperform plasma or laser systems....just as laser and plasma can outperform waterjets in some areas.
In a nutshell:
Abrasive water jet....cuts many different types of material...metals, stone, plastics, wood.....and many others.
For soft materials...straight water can be used....speeds are fast and operating cost is reasonable. Ford hard materials...such as most metals...abrasive in the form of garnet is used....this adds cost.....and the cutting speeds are quite slow.
Cut quality is very good....with no HAZ (heat affected zone)...accuracies in the .010" to .015: range on metals.
Plasma....Plasma is the productivity process...it is extremely fast on steel.
Plasma can only cut electrically conductive materials.
Plasma is fast, with low operating cost.....and accuracies in the .020" to .030" range.
Laser Laser is most comonly used on metals under 3/8" thickness.
Laser equipment has a high capital equipment cost with high operating cost....yet can be very productive and accurate on thin materials...accuracy as good as .005"
So, there may well be a market for water jet cutting in your area....but none of the cutting processes are the best at everything they do! If you cater to cutting parts for metal fabrication.... then the accuracy of the parts you produce combined with how much you charge will determine who will buy your product. With Plasma you will have high volume production with low pricess and lower accuracy......Laser will have high tolerances on thinner materials with medium cutting costs....and water jet will have good accuracy with no heat affected zone....with very high cutting costs.....yet will cut more materials.