As both companies name originate from Nikola Tesla. It looks like Nikolas's business model has been turned to vapourware overnight because of Tesla. Rumours are that Nikolas's employees are worried and blaming Elon Musk for fake stats regarding its truck.
I wouldn't go that far. Imho there is enough room in the market for both. Remember, the concept of the Nikola One is a bit different to the Tesla Semi. Both have advantages and disadvantages.
An H2 powered semi was a stillborn product to begin with. Tesla's announcement just hastened that process...