10W-30 hasn't been spec'd in years by any OEM - mainly because they want to spec a grade for the entire country, and 10W in North Dakota in the winter probably isn't the best.
Also, you can't get 10W-30 in every flavor - I think Mobil 1 has only 2 options out of there 6 different formulations. You will never see it on the walmart shelves either - again because most people just follow whats printed under the hood.
This is likely why people think its "obsolete".
In the fleet world, 10W30 has largely replaced 15W40 in semi trucks. The only new diesels we get that still use 15W40 are the spotter trucks equipped with a Cummins B6.7.
In terms of passenger car applications, I believe FCA was the last to spec 10W-30 for anything. The push to have something that works everywhere from Alaska to Arizona has driven the uptake of 0W-xx in pretty much everything and even the "old holdouts" like the HEMI, which spec'd 5W-20 have now been re-spec'd for 0W-20.
Due to this, you won't see many modern approvals (dexos for example) on a 10W-30 bottle. In terms of the OEM's for PCMO applications, it is indeed considered obsolete.
On the other hand, for HDEO applications, 10W-30 is the new 15W-40 as @skyactiv
notes. Cold climates will get spec'd with a 5W-40 or 0W-40, but the "conventional" option is now a 10W-30.
If ambient isn't going to get down to -25C (the CCS limit for 10W-xx) then it will be fine, obsolete or not.