Open source and business (making money) will always be a more complicated equation to resolve. Especially the side where the (paid for) effort you do to produce an open source product can be reused by others for free. You basically give it away. But you also get it: all the work needed to produce a full software stack (linux, jack, apache, etc) is the result of open source work. It works as intended. You enrich an ecosystem, and others will benefit from your expertise, as much as you benefit from others’ expertise.
Not always as in “they take your software and sell their product with it”. They could (should?) participate in improving mod-host/mod-ui… or not (unless the license forces them to release whatever improvement they make, but they might not make such improvements in the first place, I am not sure). But also, plugin developers could take advantage of the MOD to have a platform to use to distribute their work (and they do! see some of the comments above), so using Free Software makes things complicated, but also is a bless. I wish I could get “community upgrades” (like plugins) to improve my Zoom R24 or my Roland Fantom X8. It’s never going to happen. But MOD Dwarf (btw I just received one I ordered, knowing that the Tier 3 may still take a while), I am sure I will be able to get new plugins for years, even make my own if I have a specific need (or ask somebody to)!
I think the business model for MOD is still the hardware. The software enables the hardware and gives it value, and the hardware gives value to the software like no other (MODEP - which I have tried - and others are not in the same league). Another thing that gives special value to the hardware are the online services, and more specifically their integration with the hardware, the access to the plugin store, to the pedalboard sharing (from my perspective, the hardware should be what gives the key to these services, so it does not make sense to open them to other platforms - these are services, not software). In that respect, what needs to be communicated is that the hardware makes the software shine and that the software makes the hardware shine. You can get clones elsewhere, but it’s never going to be the same.
What I would find difficult is how to keep the balance between on one hand the one-time fee that is the hardware, and on the other hand the continuous improvements (software upgrades, plugin development) and service access (plugin store, pedalboard sharing, etc) that keep costing the company. One is of course the fact that the existence of these services gives more value to the hardware, hopefully convincing people to buy a unit. But at some point, the existing users could be willing to give more, in order to get more.
I don’t have an answer, I think putting services behind a subscription model (like Roland and others are doing) is a bad idea. I would not want to believe that I “rent” my unit, that it becomes worthless (or at least less valuable) without a monthly fee. At the same time, if I think I can get value by some subscription, that wouldn’t be lost if I stop subscribing, I might be willing to participate. E.g. if it’s a bit like a “patreon” where once a certain amount is collected, it could trigger some paid work (e.g. some specific plugin, some additional platform feature that would not otherwise be able to see the day). Everybody would benefit, even those not participating, but by participating, one would help this development to come earlier. This kind of things (not saying ALL development should be financed this way, don’t get the wrong idea! 
).
In the end, around open source software, there are generally two ways of making money: on either side of the software: the hardware and the extra services. the software itself should enrich these two, and in turn be enriched by these two. And then, you need good communication so that it is clear to everybody 
