There’s still very little concrete data on the virus itself. Whether something will become a lethal pandemic or not depends on a number of things. Incubation period, severity of initial illness, lethality, and number of people infected per case (this number is called r0. An r0 less than one will fizzle out. 1 is stableish and above 1 will spread, in very simple terms.) a virus that’s airbourne will spread further than one that needs direct contact. A virus with a long incubation period will spread further than one you fall sick immediately. A virus that kills you fast n nasty like Ebola is actually a poor pathogen because it’s easy to quarantine. It’s too lethal in a way. The andromeda strain type stuff will have a high r0, long incubation, and kill at high frequency. A new flu is ideal.
Going through media reports it seems like this virus is more contagious than SARS, which had an r0 of 4 (each case created on average four new ones) For context, measles is 18, Ebola is 2. BUT it seems less lethal, which is good. Worrying developments would be extremely widespread transmission (1/3 of the world was infected with the 1917 flu) or an increase in lethality (1917 flu killed 10-20% of those that it infected, so roughly 3-6% of the population of the planet died, in an era before air travel but also before decent nutrition was widespread and before modern medicine.)
It’s hard to say how this will pan out, but from what we see now it’s not horrific. But it could be horrific with a few tweaks if anyone has any hard epidemiology data it would be good to have.