It will be worthwhile because it is happening.
Before the 12m challenge, chasers didn’t look for activators on 12m. This was because hardly any activations included 12m. At the time, conditions were on the up and there was no real reason for 12m to be ignored in the way it was being - it just was. The 12m Challenge massively increased interest and focus, lots of SOTA activations suddenly included 12m and the chasers were keen to work them.
I’d expect a similar effect from an FT8 challenge. Like 12m was, FT8 is massively underrepresented in SOTA compared to the proportion of AR activity that is on FT8. In fact, many times moreso. So like 12m, there is a big gap there that a Challenge would help populate - and lots of activators and chasers would have a lot of fun.
Personally, I’d widen the remit to Datamodes - generally. This would make the Challenge more inclusive (and would allow the DB to continue to lump all DATA contacts together), and give those more “competitive” participants the motivation to expand their repertoire to PSK31, JT65, RTTY etc to boost their Challenge score. If using the sensible scoring algorithm that was employed in the 10m/6m Challenge, this would be a way of attracting more unique callsigns, as often the different datamodes have different cohorts of amateurs playing on them.
But yeah, the sudden boost of datamode SOTA activations itself, would prove to be the carrot for the chasers to get involved. (As indeed happened with 12m, and, a long time ago, the sort of thing that caused many of us to decided to learn CW, even though it was no longer a requirement to get access to HF).