K9 Thunder for Finland...what is the key to the future...rockets or guns?

via Defense Aerospace.

Finland will buy 48 used self-propelled howitzers from South Korea for 146 million euros. Besides the howitzers, the deal also includes training, spare parts and maintenance.
Defence Jussi Niinistö (Sannf) approved the purchase on Friday.
The new vehicles are to replace part of the Finnish army’s artillery park that will become obsolete in the 2020s and 2030s.
The first self-propelled guns will arrive in Finland next year and the final ones in 2024. Conscripts are scheduled to begin training in the new artillery system in 2019.
The Army tested the K9 Thunder self-propelled guns last year in Lapland. Their 155-millimeter guns have a range of about 40 kilometers. They have a top speed of over 60 kilometers per hour.

(EDITOR’S NOTE: The contract includes options for further procurement. The vehicles will be modified to Finnish requirements by Millog, the defense force’s logistics branch, and will generate 37 man-years of work, according to a Finnish-language statement by the Finnish MoD. Discussions are also continuing with Estonia over a possible joint procurement.) 

The Editor's Note is quite interesting.  The nexus between defense procurement and jobs is becoming a major driver.  I'm not sure whether that's a good or bad thing.  What I do know is that it is a "thing".

Many readers from Finland claim that they will now have the most powerful artillery force in the EU/NATO.  Only the US and Russia will have more powerful weapon systems.

I have to wonder though.  Which system is the key to future battlefields.  Rockets or guns?