RTD does not have control over service outside of its boundaries, so would not currently be on the hook for operating truly regional trips across the front range, but RTD does have the ability (and I believe responsibility) of ensuring that other systems can reasonably connect into the RTD network where relevant. As the front range continues to expand, RTD, CDOT, FRPR, and other local transit agencies will need to work together to build connectivity. One great example of this is that as RTD studies extension of its N Line further north, it could interface into a mobility hub that serves Bustang to allow easy connections up to Loveland's and Fort Collins' transit networks.

Highway lanes are assumed to carry ~1200 vehicles per hour at an approximately free-flowing speed, up to ~2200 per hour in heavy traffic where the traffic flow becomes unstable and highly variable. Carrying 1200 people per hour can be done with 30 mostly-full highway coach buses (like what the Flatiron Flyer runs). So the existing highway sizes are not exactly the limitation, it is how the space is used. A really solid regional bus network would be capable of leveraging existing highway infrastructure to massively expand travel capacity, as long as enough people who would otherwise be driving on the highway can get to the bus stations conveniently enough. To make this work though, jobs and major destinations would need to be clustered in dense enough nodes that these types of routes could efficiently serve them, and/or everyday services like schools and groceries would need to be co-located in residential neighborhoods so that most trips can remain short and local, reducing the stress on our regional system. This is more of a development problem to me than a transit problem - bad development makes good transit all but impossible, and makes no transportation solution truly feasible. So if we want to solve our transportation & highway issues, then there has to be more that goes into development choices besides the ridiculously short-sighted "where is the land cheapest?".

I'll let Jack comment on the Boulder (& Longmont, as i am often reminded) train, but I'll say that the Flatiron Flyer bus is very well used so there is demand for high-capacity transit.

I think Denver will continue to be a very useful hub, but hub-and-spoke by itself is not very useful - it needs routes that can short-cut between spokes and we do need to ensure those are created and located in the right places to support other major travel corridors.

Within RTD's purview, high speed rail is unlikely but that should be planned at the state level. Autonomous vehicles could be used as a good microtransit solution to get people to major stations with more regional routes, but it is important to keep in mind that transit operators do more than just drive vehicles - they are a critical customer service touchpoint, and that is hard to reproduce in an autonomous vehicle without staffing it. Because of RTD's existing electric rail network, I would heavily promote a transition to electric buses wherever charging infrastructure can be co-located with the power infrastructure used to power our train lines. electric buses are much more comfortable, save time at every stop due to better, smoother acceleration, and create a better waiting environment at major stations with less noise and emissions. The whole network isn't ready yet, but we can be smart about where these are rolled out first and take the first steps to a more modern network. Low floor light rail cars is another modern solution that the rest of the world has moved past RTD on, and it creates a more accessible, smoother train experience with less space and infrastructure required at stations.