I think that are many companies that would use a 10 wafer per hour direct write ebeam tool. Mask costs near leading edge nodes are quite expensive - as are any alternative lithography approaches. And it's likely that throughput would be even higher at higher design nodes. For small volumes and rapid prototyping it would be valuable. And of course some people would be interested in it as a faster mask writing tool.
It depends on the cost of the machine. If it's maskless and does not require expensive EUV sources and mirrors, the machine could be potentially less expensive. In that case you just buy more machines to reach the production rate you want.
Electron microscopes have been converted to e-beam litho at a cost of about $100k that produce 20nm line widths. These can be used for very limited production. The new vector scan (shaped beams) are very expensive (I think they're over $6kk per machine), which makes it questionable whether it's practical to simply add more machines to make up for the lack of processing speed.