If I were still a dub , I would reply that Jesus' followers were not appointed as apostles (with Holy Spirit) until the time of Pentecost some after his death and ascension to Heaven .... So at the time he said it, they were not apostles
NB Matthias and Paul were of course appointed later
The JW interpretation of this is that Jesus was referring to the transfiguration, which occurs a few days later.
Which is crazy - what are the chances that a number (possibly the majority) would die in the next 6 days?
And given that none of them did, it's also a false prediction.
The hoops that JW's and other Christians have to jump through to explain this scripture away!