My opinion on the current and future state of gaming and the UT franchise is this... for what it is worth...
Since the development tools are PC-based (C# and C++ Editors/Compilers, 3DS Max and Maya, PhotoShop, etc.) the tools for Epic and their Licensees will stay PC-based (UnrealEd, etc.). This is a given and won't change unless some other personal computer platform (Mac, Unix/Linux, SGI, etc.) takes over the workstation-level personal computer market share (which is highly unlikely). So the engines and tools will be developed on the PC, for the PC hardware and the current line of consoles.
Epic is one of the largest middle-ware companies now. There are currently and will be in the future, Licensees who want to create PC games with UEx and/or cross-platform games with UEx, so UEx will almost definitely support the PC hardware (Mac and Linux? Not so much... market share is too small).
Since Epic creates at least one game per platform that their engine runs on, in order for the Licensees to see a completed game with the tools they have purchased, we will still see something PC-based, whether it be "UT4 Tech Demo Game" or whatever... still... PC based...
Will there be a "full" UT4, 5, 6, ... for the PC? That is difficult to say. Only Epic knows for sure, and not even they know the entire future of computing.
The issue that I feel many game companies and PC gamers are missing is the fact that the console market is mostly the play-once and/or throw-away games and gamers. IMHO, because of this, certain game types or franchises are set to fail if they are made console-only.
The console sales on "what's cool and new" rocket up fast, beating out most PC sales of same or similar titles, but then the game is played for a shorter time and replaced by the console owner with the latest fad or "cool game" in a very quick time (days to weeks to a couple of months).
Where this doesn't fly with the PC gamers is the fact that the PC has always maintained games and franchises that had longevity.
How many XBox'ers still play their GoW? Sales were great for Epic, but how many of the total games sold are still "in-use".
If UT4+ were console only, IMHO it will fail, in that there will be little to no community and the overall longevity of play will be shorter. That is the nature of most console gamers. This game looks cool, I'll play it for a few days or weeks until it bores me (or "no longer entertains me" if you wish to be kinder and more p.c.), then it is on to the next new thing (most often a different title or franchise). And for those who might argue, well games like Halo that have multiple sequels sold well. Yes it did, but how many copies of H1/H2/H3 are still being played on the consoles (vs their total sales)? I haven't touched Halo XBox in many years. However, I still play UT99, UT2004, etc. (FEAR, Q3A, BF2142, QW, ...)
PC gamers are different. They stick to a game and/or a franchise and play it online and offline for years. Look at Sims, WoW, BF2, CS, UT99, etc.
Personally, I think a console only UT franchise game would die. Sales might be fine out-of-the-gate initially if it had "cool" or "wow" factor, but the game won't have any longevity.
Console games just don't. That is the nature of most console gamers when compared to PC gamers.
And most console games also don't survive the hardware upgrade path (how many total Xbox games play on the 360?). PC games often do still play upwards (I still play Q3A on newer hardware after probably five or six upgrades since it's release and love it).
Even though GoW XB360 has sold probably 10x of UT3 PC, a year from now there will be more people still playing UT3 PC than GoW XB360, if anyone even plays GoW at all by that time. But companies need income, and consoles are where the sales and money are, so that is where companies will go.