So we're going to have some engineers specify suitable digital replacements given the process/environment/safety requirements. We'll procure those (noting that an industrial digital pressure transducer can easily push up towards $10k), schedule a plant shutdown (how much does that cost?), then pay a pipefitter/boilermaker to replace the old gauges with new pressure transmitters (do you need a hot work permit for that? Did you get your engineer to sign that off?). Then, your controls sparky has to find a way to route a drop back to your marshalling cabinet for connection into your fieldbus/HART/modbus/whatever network (do you have one of those?) so that your SCADA system can talk to it (do you have one of those?).
Obviously it's not really an apples-to-apples comparison, but I think the costs involved with making "simple" changes in industrial settings are easy to wildly underestimate.
Dumb silicon is so super cheap now, just look to nfc etc, 1c microcontrollers. We can litter our world with sensors.
Which I would love to see - but I'm also not discounting the usefulness of any robot just being able to read something we can read and vice versa.
If it ain't broke don't fix it — pointing a cheap camera at it with some cloud compute will suffice.
Like your washing machine reporting its state, knowing if sun is out, running only when there is a lot of sun.
Your bsement heater sending out its stats.
And your industry machine doing the same thing.
Then you realize that we are talking about industry 4.0 for a decade now, everything IoT is either closed source or always costs extra and working together? hahahaahha...
I don't know why we can't have nice things it would be that easy :|