question about sudden dynamic changes

Hello. I am a composer and have a couple of questions about the practicality of a particular bowing situation.

I've written a part for violin in which the tempo is quarter note = 92. At one point the violinist plays the open E string for two beats, crescendos from pianissimo at the beginning to forte at the very end of the half note, and then on beat three plays the first E harmonic on the same string at subito piano.

Is it difficult for a professional player to makes the sudden dynamic change in this situation, without a break between the two notes other than a change in bowing direction?

Also, are there any potential problems with going from an open string to a harmonic in this way?

Thanks in advance for your responses.