Maybe similar to an old SmartThings sensor?
Maybe a rule to trigger a local endpoint every 20 seconds, like the ST arrival sensor.
Variables. Compare, I don't know. If it can't make the device do something or other, it's absent.
It'd be cool if it could be done.
Maybe one of these wired to the battery of a contact sensor wired closed.
Excuse my ignorance... And assuming your original proposition is for a contact sensor to be located inside a car.... Admittendly not handling the returning of someone on foot....
I am not sure about the time it takes for devices like these to re-join the network, i.e. once you arrive home... but would this not pose an inconsistent experience depending on the time this takes?
As an alternative could the contact sensor, and perhaps more than one, not be placed on doorways used as entrances to the home? So a garage door, front door... etc? Then once they open transition the HE hub from Away to Day/Evening/....?
I'm looking for an alternative to the discontinued SmartThings Arrival Sensor.
I am sure I have purchased Aeotec contact sensors since Samsung excited the market, but I could be wrong... Either way, I would still expect there is at least one contact sensor still on the market and able to do what I described. Would a contact sensor (or sensors) not provide what you need, where they are placed on external doors?
Since the OP asked for specific solution I took a swing. The idea there is that you can very simply control an interval for zigbee communication from a battery powered device. This using the item suggested by the OP.
BLE and beacons are an alternative. Either with them stationary with a moving base or moving with a stationary base.
If you just need arrival like as in you arriving home from work I'd imagine any geofencing could work using your phone.
Holy Crap.
The Xfininity contact sensor, which I have a few, works perfectly with the SmartThings Presence Sensor V4 Hubitat driver! The log below is me putting the sensor in and out of an Altoid tin and a covered pan (must be strong radio, or weak metal, lol). The settings on the driver are defaults. Two minute departure. Check it out:
Glad you have found a likely candidate solution... try leaving the property / vicinity for a period beyond 20 minutes.
There have been many fans of the SmartThings arrival sensor, I believe.
I'm going to substitute this for my ST sensor in rules, put it on the dash, or velcro it next to the ST sensor, and see how it works.
It has a larger battery than the ST sensor-still a coin format, but larger. I forget the number. So, maybe longer life. It also has a similar range. I used it at one time on my far flung driveway gate-it was just on the edge.
I'm psyched about this.
Will do. Never a problem for the ST Arrival Sensor.
Not all devices are made equal.... Sadly... Basically wanting to assess the performance of the device when it enters what others call the "panic" mode, when it tries to find a new / optimal path back to a controller, and whether this time may impact your experience in detecting returning home. I'm such a killjoy.... 
Perhaps the fact that I have no repeaters will help, lol.
Yep, that's something we should promote... 
Only if you want rock-solid reliability.
Note that hub is on a battery, unlike most every other powered repeater.
That Xfinity Contact sensor is actually very amazing (it's really the Visonic MCT-350). It also reports temperature. However, in my personal testing, I find that it works even better when there is a Zigbee repeater nearby.
Isn't there a limit to the number of Zigbee sensors that can connect directly to the hub. Is it 32?
P.S. I find that its also sensitive to moisture (condensation on the contacts, due to cold Canadian weather. So, I encase the sensor in scotch tape, to not allow warm air inside.
I think it used to be. I don't know what it is now.
My gut feel it's a Zigbee standard thing.... Not dictated by the device.... Again just my gut feel....
How long will the battery last?
The ST sensor lasts 4-6 weeks with a name brand CR2032 battery.
The Xfinity sensor has a CR2450.
If the setup works, we'll see how long the battery lasts, but it wasn't fresh.
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