In terms of the future for Reynolds as well as the rest of these wideouts on the depth chart and PS, they have to "fit" in a few ways to stick around and factor in:
1. Hands. McVay is not going to keep a wideout around for long if the dude has iffy hands. He'll be phased out, all while Sean and Les say great things about him like we saw with Tavon. You just can't have dudes dropping passes in certain situations in this offense, as we see with Woods, Kupp, and Cooks all three being different types of wideouts physically but all three have things in common which of course are listed here.
2. Route precision. We've talked about this before but the Gruden offense when done right has wideouts running a collection of routes to exact depth challenging different DBs & parts of the field. This also translates into separation as well so it's crucial.
3. Positional flexibility/smarts. Sean loves guys who can take to his coaching of advanced concepts. Dudes who are stupid or slow to get an offense are just not going to compete well for a guy like him. We're seeing that translate right now in them bringing in a guy who's a marginal talent that has a very good grasp of the offense. In other words being in the wrong spot on a given play can result in turnovers and the kind of bad field position flips that we used to be plagued with.
In no way does Reynolds translate well to that list above as of yet. He might eventually, although it doesn't seem to me that there are very many wideouts who show huge strides at this level in the hands dept, typically if you don't have that you're going to struggle when DBs are right on you. Good thing is a lot of wideouts do show big improvement in route running and understanding concepts, so it's not like these guys can't work their way into being a good wideout.
And lastly for those who think that doubting him means we're hating on the dude, it doesn't. It just means he's got a lot to prove.