But i would not say that "a miner's coin" is automatically useless for merchant adoption and daily business.
Im talking about valuation which most (not all) people are concerned about.
A miners coin is by default a "easy" gateway to access BTC by the common person. This will, by its very nature, have a constant downwards pressure on the value of that coin aside from the occasional pump.
In terms of adoption, lets be realistic. No other mainstream coin will usurp BTC at least for the time being. If something does down the line, it will be something that is new and not out on the market yet. Anyone who says that VTC can gain adoption is naive. What evidence is there that that is even a remote possibility? What is being done on that front? nothing. There have been 2-3 major pushes in the last ~11 months and the best that could be done is coffee, hotsauce and games. The closest we came to a concerted effort on that front was Vertpay, which was a clusterfuck. And a few months later that team (who are well known in the crypto community) even said that it probably would not have worked after they did some research, there is not enough demand in the outside market. The only merchant adoption that is possible is through something like moolah or its equivalents, which is meaningless if that service allows for 10 other coins besides Vert.
BTc is "mainstream" and that wont change, no coin has the resources to challenge its community, headstart and expertise, things like ethereum might/might not work, and there will be a niche for a good anon coin. Vtc droppped the ball on the last point.