Henk, you can do this right now using post-job script to upload produced backup files to FTP server. It is unlikely that we will ever provide the ability to specify FTP as actual target for job, because Veeam Backup uses synthetic backup which requires fast storage by its nature (otherwise incremental backup performance will be terrible).
Please put this into your product as an offsite copy option as most other products have. I was recently attacked with a dharma .wallet encryption ransomware and all of the backups are worthless now as my NAS was also encrypted. Every backup that I had was encrypted and unrecoverable. To put offsite copy option and scheduler for once a week full backup would be so beneficial.
Images will be automatically duplicated to FTP with the completion of backup.