I'm not much one for mini games, but that is because my definition of mini-games is stuff like treasure hunt and arena, where you engage in something that has nothing to do with the main game as a whole (your kingdom progression, troops, banners, stat boosts.. all meaningless). I'd love more modes where we could engage in otherwise normal battles with different rulesets, with perhaps some restrictions on what should be used.
I'd also really like if these alternate modes were alternate paths to get existing rewards and required to get some exclusive thing so that people that like it can play it and people that don't feel obligated, because that is a huge part of what makes guild wars so divisive in the first place. I'd have loved a guild-wars style challenge mode that meted out personal rewards for a certain amount of consecutive wins versus increasing difficulty, deliberately designed fights. I could do without a treasure hunt 2.0, especially if it is decided that there is a "treasure hunt 2.0 troop" and you have to play treasure hunt 2.0 in order to get this troop.
On the monetization side, there is a lot they need to fix. Gem prices have not been updated ever, and they continued to be devalued on multiple fronts every week - you need more to hunt specific troops every time a troop ultra-rare or above is added, you have less probability to get something useful from any gem purchase the more gems you have AND the baseline amount of gems an average player will earn has gone way up. I just don't see how continued (informed) gem purchases are expected when people are flipping literally tens of thousands of gems worth of gem/event keys chasing a drop and coming up empty as the norm.
Hopefully crafting will address this by assigning permanent, fixed costs to what this supposedly premium currency can buy you in terms of what it is by in large used for, the acquisition of troops, but as of now, it is pretty out of control and that is why there isn't really any room for frivolous stuff costing gems - you don't use them for "other stuff" (armors not withstanding) unless you are super flush with gems and it doesn't lead to actual cash purchases, or just uninformed which can lead to people feeling "tricked" and harms the game in the long run.
Going forward, we also need at least some monetization options that scale to all levels of play. The $5 weapon packs are a nice start, either you have them or you don't, they aren't overly expensive and bloated down with too much "bonus" stuff that doesn't scale. Guild seals are nice if you needed some people to chip in to reach 40k so your entire guild can benefit, but the $20 pack amounts to basically 25 gem key drops and 25 guardian troops (or 50 gem key drops), tops, so they are pretty useless to people in guilds already getting 40k or those that 40k is a distant pipe dream. Deathknight Amor pack is generally lauded as having the most long term value of any purchasable item in GoW has some lasting benefit, but even that drops off considerably when you are level 1000+ and don't have anything else to spend souls on. Reasonably priced cosmetics I wouldn't have a problem with.. only this isn't the type of game where you interact directly with other players outside of them briefly seeing your avatar in a menu somewhere, so it isn't exactly the best fit.
What else could we have purchasable? Timed or subscription style service buffs to your global gold bonus (or souls/xp, either combined or at a much higher rate) perhaps? Maybe a traitstone drops buff? Or a true subscription style purchase that increases all earnings from all sources by a certain percent?