As WT is less than forthcoming in regard to presenting an audited financial statement to the public, financial difficulty is only speculation as are other reasons.
Perhaps, they have run out of ideas for BS to present.
Ex-JWs form a substantial segment of JW Broadcasting viewership. There are several review sites which scrutinize each program's content word-for-word. Misinformation and lies are highlighted as are changes to past doctrines. WT has attempted to have some of those sites shut-down, often unsuccessfully.
How long would it take for JW Broadcast presenters to become disheartened and less than enthusiastic in taking their turn to present a monthly broadcast, when they know their every word is critiqued and scoffed at on a public forum?
The audience for a broadcast (webcast) program is not restricted, unlike the audience at a Kingdom Hall or for private, closed circuit video content.
With regard to costs, how substantial do you think production costs are for a 1X per month, 1+ hour 'talk' show using 2 cameras, featuring 1, maybe 2 non-talent staff people, within a news style set format that hasn't changed in several years use?
For a brief explanation of content changes, see the initial 1:30 of the December 2017 video at the link below:
December 2017 video
It appears GB plan to regularly recycle talks they have already produced for other purposes.