Question: I suspect being economically strong and independent aren't enough to become a super power in today world, I realised that US is slowly losing it's grip as a super power after it starts shifting focus on other research areas and staying away from making nukes. Given today technology, can a nation become a super power without having any nuclear programme? Sorry for my childish thinking but I think people would definitely listen when you can talk at over 250dB.

Answer: 
**First to achieve Lunar/Space Colony.**

Say a multibillionaire sets his sights on space exploration. Before the slow engines of states achieve similar success, his country could be lauded SuperPower if they get first De FACTO ownership of celestial bodies.

The logistical capabilities that accomplishment grants, the information available to them. 

*And the sheer Bragging Rights.*

That makes you the sole state who controls a rare commodity, akin to China holding the Lion's share of rare earths.

Remember that Politics is the Art of looking the part.
Power Projection
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There is debate within the political science community as to what defines a super power. However, a good proxy is the ability to project power.

The UK was the dominant world power during the colonial era. Few people would argue this, yet they certainly didn't have nuclear weapons. The UK could, however, blockade ports, draw on a vast empire for soldiers, and support sustained conflict anywhere on the globe.

China Today
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In fact, the lack of blue water naval power is why I would not classify current day (2020) China as a superpower. ICBMs are really the only way that China can threaten countries outside of Asia. Contrast this with the current US capabilities and Cold War Era USSR power projection - either one was able to land and support troops at far removed locations.

Soft Power
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Economic pressure is certainly a way to project power - sanctions can hurt. But I think it is insufficient.

Bottom Line
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Can the nation transport and sustain large bodies of soldiers to distant locations in the face of armed resistance?

Nuclear weapons would only play into this definition if we posit that Mutually Assured Destruction is required to prevent the other party from using Nukes to prevent landing or sustaining those troops.