if they did move to online-only... it'd mean they could do interesting things with contactless in general rather than simply foist a fixed limit on everyone. in addition to what i wrote above about China UnionPay, for debit cards you can set aside whatever amount of money you want and this is treated like cash - no pin would be required til its gone, however much you've put in. you could set aside £200 and use that in one transaction if you wanted... or you could have 0 and then you'd have to authenticate every transaction with a pin. it'd surely be better than the status quo, and eliminate a lot of the "omg i don't want contactless on my card" worries a lot of us brits seem have.
I can understand why some people have concerns with contactless payments (given the recent news) but that'd be a good idea.
For example: TSB offer 5% cashback on contactless/Apple Pay payments up to £100. Rather than splitting the cost in most retailers you'd then be able to spend £100 in one go and earn the £5 reward.