PS4 Neo won't shorten PS4's lifecycle, "PS4 is PS4"

Just as an establishment over how Neo will operate in conjuction with the existing PS4, similar to whats been established about Scorpio, PS4 will serve as the more affordable standard whilst Neo will serve as the higher-end edition. Support will be mandatory for the PS4 and Neo.

The interviewer asks if the generation is ending quickly in favour of hardware progressing in smaller and more frequent steps

Yoshida responds:
Well no, PS4 is PS4, you know the new high end PS4 is still PS4, so you know the lifecycle is not going to be shorter

This should clear up any worries, but we are now beyond generations. Scorpio and Neo will not force you to abandon your existing PS4/XB1 library and accessories, they will be all compatible with the console succeeding them.