UMA is still a go to MTG product. Atm the average EV of UMA is $299Usd, though i believe that's with a fair bit of singles saturating the market from the expected pack openings. Granted it's a reprint set and there can always be potential for another reprint (set/product) down the line. Though with the recent Modern Horizons/MH1 set announcement of pretty much all brand new Modern staples i do not think there would be a reprint of UMA cards for at least 2+ years (should the reprint occur) and even then i believe the cards will retain at least similar values as we have today (which are relatively reasonable or even low). (I personally do not think MH1 will change the existing competitive (tier1) decks but will improve existing tier 1.5-2 decks). Also UMA has a limited print run (possibly similar to Revised/3E back in 1994) with Box toppers/BT having a big demand (though the foil mythics in the set are twice as rare as mythic BTs (20 of 40 total BTs), 0.5 to 0.25 chance/booster box). The extra BTs average $77Usd currently. With regards the mythic/M and rare/R cards, they currently average at $8Usd/ea per booster box (say at 21 rares, 3 mythics per box). Though UMA's (msrp) price point is approx 3.5x the usual booster box it still averages better than the current average of M and R cards in the most recent Ravnica Allegiance/RNA and Guilds of Ravnica/GRN standard block sets which average about $2.17-2.22 ea M or R. The RNA and GRN average price of M/R's usually is the highest price at any time as per usual normal/block sets as opposed to UMA which includes many popular and playable cards in the most popular formats of Magic (albeit reprints). On top of this, in UMA you have a foil in every pack i.e. 24 as opposed to ～6 foils in a regular booster box, that's not a great deal more but is still 3 more foils than 3.5xreg booster box. Though you would get 3.5 Rare/R foils with the standard booster boxes as opposed to 2 R foils with UMA. You do not get many Magic sets at all that have EV's at 80+% of MSRP. Other sets have to heavily discount their normal booster boxes to sell e.g. 70%～or less of MTRP.
TLDR: Ultimate Masters/UMA compared with other MTG booster boxes is still underpriced and still a real possibility of a solid buy for Modern staples, play, fun and/or investment.